first commit

CHELLO - Hello World.java

@@ -0,0 +1,5 @@
+public class Main{
+    public static void main(String[] args){
+        System.out.println("Hello PTIT.");
+    }
+}

HELLOFILE - HELLO FILE.java

@@ -0,0 +1,18 @@
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.Scanner;
+
+public class Main{
+    public static void main(String[] args){
+        File file = new File("Hello.txt");
+        try{
+            Scanner scaner = new Scanner(file);
+            while(scaner.hasNextLine()){
+                System.out.println(scaner.nextLine());
+            }
+            scaner.close();
+        }catch(FileNotFoundException e){
+
+        }
+    }
+}

HELLOJAR - HỌC PHÍ.java

@@ -0,0 +1,62 @@
+
+package nyagami;
+import java.io.*;
+import java.util.*;
+import view.InvoiceView;
+import vn.edu.ptit.*;
+/**
+ *
+ * @author hoang
+ */
+
+
+public class Nyagami {
+    
+    static class PaymentController{
+        private Invoice invoice;
+        
+        public PaymentController(){
+            Scanner sc = new Scanner(System.in);
+            
+            Student st = new Student(sc.nextLine(), sc.nextLine());
+            
+            int n_subject = Integer.parseInt(sc.nextLine());
+            ArrayList<Subject> AlSubject = new ArrayList<>();
+            
+            for(int i=0; i<n_subject;i++){
+                String code = sc.nextLine();
+                String name = sc.nextLine();
+                AlSubject.add(new Subject(name, code, Integer.parseInt(sc.nextLine())));
+            }
+            
+            Rule rule = new Rule(sc.nextLine(), sc.nextLine(), Double.parseDouble(sc.nextLine()));
+            
+            invoice = new Invoice(rule);
+            invoice.setSt(st);
+            invoice.setAlSubject(AlSubject);
+            double amount = 0;
+            for(Subject sj: AlSubject){
+                amount += sj.getCredit()*rule.getCreditPrice();
+            }
+            invoice.setAmount(amount);
+        }
+        
+        public Invoice getInvoice(){
+            return invoice;
+        }
+    }
+    
+    public static void main(String[] args) {
+        PaymentController pc = new PaymentController();
+        //Output for test
+        Invoice invoice = pc.getInvoice();
+        InvoiceView.show(invoice);
+    }
+    public static void main5399814(String[] args) {
+      PaymentController pc = new PaymentController();
+      //Output for test
+      Invoice invoice = pc.getInvoice();
+      InvoiceView.show(invoice);
+  }
+}
+

J01001 - HÌNH CHỮ NHẬT.java

@@ -0,0 +1,16 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        int a = reader.nextInt(), b = reader.nextInt();
+        if(a<=0 || b<=0){
+            reader.close();
+            System.out.print(0);
+            return;
+        }
+        String ans = String.format("%d %d",2*(a+b),a*b);
+        System.out.print(ans);
+        reader.close();
+    }
+}

J01002 - TÍNH TỔNG.java

@@ -0,0 +1,14 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        while(t>0){
+            t--;
+            Long n = reader.nextLong();
+            System.out.println(n*(n+1)/2);
+        }
+        reader.close();
+    }
+}

J01003 - GIẢI PHƯƠNG TRÌNH BẬC NHẤT.java

@@ -0,0 +1,15 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args){
+        Scanner reader = new Scanner(System.in);
+        float a = reader.nextFloat(), b = reader.nextFloat();
+        if(a==0){
+            if(b!=0) System.out.println("VN");
+            else System.out.println("VSN");
+        }else{
+            System.out.printf("%.2f", -b/a);
+        }
+        reader.close();
+    }
+}

J01004 - SỐ NGUYÊN TỐ.java

@@ -0,0 +1,25 @@
+import java.util.Scanner;
+
+public class Main {
+
+    static boolean nt(int n){
+        if(n<2) return false;
+        if(n==2) return true;
+        if(n%2==0) return false;
+        for(int i=3;i<=Math.sqrt(n);i+=2){
+            if(n%i==0) return false;   
+        }
+        return true;
+    }
+    public static void main(String[] args){
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        while(t>0){
+            t--;
+            int n = reader.nextInt();
+            if(nt(n)) System.out.println("YES");
+            else System.out.println("NO");
+        }
+        reader.close();
+    }
+}

J01005 - CHIA TAM GIÁC.java

@@ -0,0 +1,19 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args){
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        while(t>0){
+            t--;
+            double n = reader.nextDouble(), h = reader.nextDouble();
+            for(double i = 1; i < n; i++){
+                double p = i/n;
+                double curh = h*(Math.sqrt(p));
+                System.out.printf("%.6f ",curh);
+            }
+            System.out.println("");
+        }
+        reader.close();
+    }
+}

J01006 - TÍNH SỐ FIBONACCI.java

@@ -0,0 +1,16 @@
+import java.util.Scanner;
+
+public class Main {
+    public static void main(String[] args){
+        long[] f = new long[94];
+        f[0]=0; f[1]=1;
+        for(int i=2;i<=92;i++) f[i]=f[i-1]+f[i-2];
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        while(t>0){
+            t--;
+            System.out.println(f[reader.nextInt()]);
+        }
+        reader.close();
+    }
+}

J01007 - KIỂM TRA SỐ FIBONACCI.java

@@ -0,0 +1,26 @@
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args){
+        long[] f = new long[94];
+        f[0]=0; f[1]=1;
+        for(int i=2;i<=92;i++) f[i]=f[i-1]+f[i-2];
+
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        while(t>0){
+            t--;
+            long n = reader.nextLong();
+            if(isfi(n,f)) System.out.println("YES");
+            else System.out.println("NO");
+        }
+        reader.close();
+    }
+    static boolean isfi(long n,long[] f){
+        for(int i=0;i<=92;i++){
+            if(n==f[i]) return true;
+        }
+        return false;
+    }
+}

J01008 - PHÂN TÍCH THỪA SỐ NGUYÊN TỐ.java

@@ -0,0 +1,29 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        for(int i=1; i<=t; i++){
+            int n = sc.nextInt();
+            System.out.printf("Test %d: ",i);
+            int can = (int) Math.sqrt((double)n);
+            for(int j=2; j<=can; j++){
+                int cnt=0;
+                while(n%j==0){
+                    n/=j;
+                    cnt++;
+                }
+                if(cnt>0){
+                    System.out.printf("%d(%d) ", j, cnt);
+                }
+            }
+            if(n>1) System.out.printf("%d(1)", n);
+            System.out.println("");
+        }
+        sc.close();
+    }
+}

J01009 - TỔNG GIAI THỪA.java

@@ -0,0 +1,30 @@
+/*
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Main.java to edit this template
+ */
+package test;
+import java.util.Scanner;
+/**
+ *
+ * @author hoang
+ */
+public class Test {
+
+    /**
+     * @param args the command line arguments
+     */
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        long n = reader.nextLong();
+        long ans = 0;
+        long[] f = new long[22];
+        f[0]=1;
+        for(int i=1; i<=n ; i++){
+            f[i]=f[i-1]*i;
+            ans+=f[i];
+        }
+        System.out.print(ans);
+        reader.close();
+    }
+    
+}

J01010 - CẮT ĐÔI.java

@@ -0,0 +1,37 @@
+
+import java.util.Scanner;
+public class Main {
+    static char convert(char x) {
+        if (x == '0')
+            return '0';
+        if (x == '1')
+            return '1';
+        if (x == '8')
+            return '0';
+        if (x == '9')
+            return '0';
+        return '2';
+    }
+
+    static String ans(char[] a) {
+        for (int i = 0; i < a.length; i++) {
+            a[i] = convert(a[i]);
+            if (a[i] == '2')
+                return "INVALID";
+        }
+        String s = new String(a);
+        s=s.replaceFirst("^0+", "");  
+        if ("".equals(s)) return "INVALID";
+        return s;
+    }
+
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        int t = Integer.parseInt(reader.nextLine());
+        for (int i = 0; i < t; i++) {
+            String s = reader.nextLine();
+            System.out.println(ans(s.toCharArray()));
+        }
+        reader.close();
+    }
+}

J01011 - BỘI SỐ CHUNG - ƯỚC SỐ CHUNG.java

@@ -0,0 +1,23 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static long gcd(long a, long b){
+        if(b==0) return a;
+        return gcd(b,a%b);
+    }
+
+    static long lcm(long a,long b){
+        return a*b/gcd(a,b);
+    }
+
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        for (int i = 0; i < t; i++) {
+            int a=reader.nextInt(), b=reader.nextInt();
+            System.out.printf("%d %d\n",lcm(a,b),gcd(a,b));
+        }
+        reader.close();
+    }
+}

J01012 - ƯỚC SỐ CHIA HẾT CHO 2.java

@@ -0,0 +1,28 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static int count(int n){
+        if(n%2==1) return 0;
+        int can=(int) Math.sqrt((double) n);
+        int c=0;
+        for(int i=1;i<=can;i++){
+            if(n%i==0){
+                if(i%2==0) c++;
+                if((n/i)%2==0) c++;
+            }
+        }
+        if(can*can==n && can%2==0) c--;
+        return c;
+    }
+
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        int t = reader.nextInt();
+        for (int i = 0; i < t; i++) {
+            int a=reader.nextInt();
+            System.out.println(count(a));
+        }
+        reader.close();
+    }
+}

J01013 - TỔNG ƯỚC SỐ - 1.java

@@ -0,0 +1,30 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static long[] f = new long[2000001];
+    
+    public static void main(String[] args) {
+        for(int i=0;i<2000001;i++){
+            f[i]=0;
+            Boolean oke=true;
+            for(int j=2;j<=(int)Math.sqrt(i);j++){
+                if(i%j==0){
+                    f[i]=f[j]+f[i/j];
+                    oke=false;
+                    break;
+                }
+            }
+            if(oke) f[i]=i;
+        }
+        Scanner reader = new Scanner(System.in);
+        long t = reader.nextLong();
+        long s=0;
+        for (long i = 0; i < t; i++) {
+            int a=reader.nextInt();
+            s+=f[a];
+        }
+        System.out.print(s);
+        reader.close();
+    }
+}

J01014 - ƯỚC SỐ NGUYÊN TỐ LỚN NHẤT.java

@@ -0,0 +1,26 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static long[] f = new long[2000001];
+    
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        long t = reader.nextLong();
+        for (long i = 0; i < t; i++) {
+            long ans=1;
+            long a=reader.nextLong();
+            for(long j=2;j<=(long)Math.sqrt(a);j++){
+                if(a%j==0){
+                    ans=j;
+                    while(a%j==0){
+                        a/=j;
+                    }
+                }
+            }
+            if(a>1) ans=a;
+            System.out.println(ans);
+        }
+        reader.close();
+    }
+}

J01016 - CHỮ SỐ 4 VÀ CHỮ SỐ 7.java

@@ -0,0 +1,17 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static long[] f = new long[2000001];
+    
+    public static void main(String[] args) {
+        Scanner reader = new Scanner(System.in);
+        String s = reader.next();
+        int c=0;
+        for(int i=0;i<s.length();i++){
+            if(s.charAt(i)=='4' || s.charAt(i)=='7') c++;
+        }
+        System.out.print((c==4 || c==7)?"YES":"NO");
+        reader.close();
+    }
+}

J01017 - SỐ LIỀN KỀ.java

@@ -0,0 +1,22 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static String check(String s){
+        for(int i=1;i<s.length();i++){
+            int x=s.charAt(i)-s.charAt(i-1);
+            if(x!=1 && x!=-1) return "NO";
+        }
+        return "YES";
+    }    
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        for(int i=0;i<t;i++){
+            String s=sc.next();
+            System.out.println(check(s));
+        }
+        sc.close();
+    }
+}

J01018 - SỐ KHÔNG LIỀN KỀ.java

@@ -0,0 +1,25 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static String check(String s){
+        int sum=s.charAt(0)-'0';
+        for(int i=1;i<s.length();i++){
+            sum+=s.charAt(i)-'0';
+            int x=s.charAt(i)-s.charAt(i-1);
+            if(x!=2 && x!=-2) return "NO";
+        }
+        if(sum%10!=0) return "NO";
+        return "YES";
+    }    
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        for(int i=0;i<t;i++){
+            String s=sc.next();
+            System.out.println(check(s));
+        }
+        sc.close();
+    }
+}

J01020 - ĐẦY ĐỦ CÁC CHỮ SỐ.java

@@ -0,0 +1,30 @@
+import java.util.*;
+
+public class non {
+    static long ans = (1<<10) - 1;
+
+    static void solve(long n){
+        if(n==0){
+            System.out.println("Impossible");
+            return;
+        }
+        long r = 0;
+        for(long i=1;i<1000000;++i){
+            long x=i*n;
+            while(x>0){
+                r|=(1<<(x%10));
+                x/=10;
+            }
+            if(r==ans){
+                System.out.println(i*n);
+                return;
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int T = sc.nextInt();
+        while(T-->0) solve(sc.nextLong());
+    }
+}

J01021 - TÍNH LŨY THỪA.java

@@ -0,0 +1,23 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static long mod=1000000007;
+
+    static long mod(long a,long b){
+        if(b==0) return 1;
+        if(b%2==1) return mod(a,b-1)*a%mod;
+        long p=mod(a,b/2);
+        return p*p%mod;
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        while(true){
+            long a=sc.nextLong(), b=sc.nextLong();
+            if(a==0 && b==0) break;
+            System.out.println(mod(a,b));
+        }
+        sc.close();
+    }
+}

J01022 - XÂU NHỊ PHÂN.java

@@ -0,0 +1,31 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    
+    static long[] f = new long[94];
+    
+    static int Try(int n, long k){
+        if(n==1) return 0;
+        if(n==2) return 1;
+        if(k<=f[n-2]) return Try(n-2,k);
+        return Try(n-1,k-f[n-2]);
+    }
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        f[0]=0;
+        f[1]=1;
+        for(int i=2;i<94;i++){
+            f[i]=f[i-1]+f[i-2];
+        }
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt();
+            long k = sc.nextLong();
+            System.out.println(Try(n, k));
+        }
+        sc.close();
+    }
+}

J01023 - TOÁN LỚP BA.java

@@ -0,0 +1,63 @@
+import java.util.*;
+
+public class non {
+
+    static ArrayList<String> genn(String s){
+        ArrayList<String> a = new ArrayList<>();
+        if(s.charAt(0) == '?'){
+            for(char c = '1'; c <= '9'; c++) a.add(c + "" + s.charAt(1));
+        }else a.add(s);
+        if(s.charAt(1) == '?'){
+            ArrayList<String> ans = new ArrayList<>();
+            for(String i : a){
+                for(char c = '0'; c <= '9'; c++) ans.add(i.charAt(0) + "" + c);
+            }
+            return ans;
+        }
+        return a;
+    }
+
+    static String geno(String s){
+        if(s.charAt(0) == '?') return "+-";
+        return s;
+    }
+
+    static int cal(int a, int b, char op){
+        if(op == '+') return a+b;
+        return a-b;
+    }
+
+    static boolean check(String a, char op, String b, String c){
+        if("*/".indexOf(op) > -1) return false;
+        int x = Integer.parseInt(a);
+        int y = Integer.parseInt(b);
+        int z = Integer.parseInt(c);
+        return x>9 && y>9 && z>9 && cal(x, y, op) == z;
+    }
+
+    static void solve(String a, String op, String b, String equal, String c){
+        ArrayList<String> arr1 = genn(a);
+        ArrayList<String> arr2 = genn(b);
+        ArrayList<String> arr3 = genn(c);
+        op = geno(op);
+        for(String i:arr1){
+            for(String j:arr2){
+                for(String k:arr3){
+                    for(int u=0;u<op.length();u++){
+                        if(check(i, op.charAt(u), j, k)){
+                            System.out.println(String.format("%s %c %s = %s", i, op.charAt(u), j, k));
+                            return;
+                        }
+                    }
+                }
+            }
+        }
+        System.out.println("WRONG PROBLEM!");
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int T = sc.nextInt();
+        while(T-->0) solve(sc.next(), sc.next(), sc.next(), sc.next(), sc.next());
+    }
+}

J01024 - SỐ TAM PHÂN.java

@@ -0,0 +1,21 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static String check(String s){
+        for(int i=0;i<s.length();i++){
+            if("012".indexOf(s.charAt(i))==-1) return "NO";
+        }
+        return "YES";
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        for(int i=0;i<t;i++){
+            String s=sc.next();
+            System.out.println(check(s));
+        }
+        sc.close();
+    }
+}

J01025 - HÌNH VUÔNG.java

@@ -0,0 +1,22 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    static int min4(int a,int b,int c,int d){
+        return Math.min(Math.min(Math.min(a, b),c),d);
+    }
+    static int max4(int a,int b,int c,int d){
+        return Math.max(Math.max(Math.max(a, b),c),d);
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int a1x = sc.nextInt(), a1y = sc.nextInt(), a2x = sc.nextInt(), a2y = sc.nextInt();
+        int b1x = sc.nextInt(), b1y = sc.nextInt(), b2x = sc.nextInt(), b2y = sc.nextInt();
+        int minx = min4(a1x,a2x,b1x,b2x), maxx = max4(a1x,a2x,b1x,b2x);
+        int miny = min4(a1y,a2y,b1y,b2y), maxy = max4(a1y,a2y,b1y,b2y);
+        int c = Math.max(maxx-minx, maxy-miny);
+        System.out.print(c*c);
+        sc.close();
+    }
+}

J01026 - SỐ CHÍNH PHƯƠNG.java

@@ -0,0 +1,19 @@
+
+import java.util.Scanner;
+public class Main {
+
+    static String cp(int n){
+        int x=(int)Math.sqrt((double)n);
+        return x*x==n?"YES":"NO";
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        for(int i=0;i<t;i++){
+            int s=sc.nextInt();
+            System.out.println(cp(s));
+        }
+        sc.close();
+    }
+}

J02004 - MẢNG ĐỐI XỨNG.java

@@ -0,0 +1,23 @@
+
+import java.util.Scanner;
+public class Main {
+    static String check(int[] a, int n){
+        for(int i=0;i<n;i++){
+            if(a[i]!=a[n-i-1]) return "NO";
+        }
+        return "YES";
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        for(int j=0;j<t;j++){
+            int n = sc.nextInt();
+            int[] a = new int[n];
+            for(int i=0;i<n;i++){
+                a[i] = sc.nextInt();
+            }
+            System.out.println(check(a,n));
+        }
+        sc.close();
+    }
+}

J02005 - GIAO CỦA HAI DÃY SỐ.java

@@ -0,0 +1,35 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.TreeSet;
+
+public class test{
+    
+    static boolean has(int[] a, int n, int x){
+        for(int i=0;i<n;i++) if(a[i]==x) return true;
+        return false;
+    }
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        TreeSet<Integer> h = new TreeSet<>();
+        int n = sc.nextInt(), m = sc.nextInt();
+        int[] a = new int[n];
+        int[] b = new int[m];
+        for(int i=0;i<n;i++){
+            a[i]=sc.nextInt();
+        }
+        for(int i=0;i<m;i++){
+            b[i]=sc.nextInt();
+        }
+        for(int i=0;i<n;i++){
+            if(has(b,m,a[i])){
+                h.add(a[i]);
+            }
+        }
+        h.forEach((k)->{
+            System.out.printf("%d ", k);
+        });
+        sc.close();
+    }
+}

J02006 - HỢP CỦA HAI DÃY SỐ.java

@@ -0,0 +1,33 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.TreeSet;
+import java.util.HashSet;
+
+public class test{
+    
+    static boolean has(int[] a, int n, int x){
+        for(int i=0;i<n;i++) if(a[i]==x) return true;
+        return false;
+    }
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        TreeSet<Integer> h = new TreeSet<>();
+        HashSet<Integer> a = new HashSet<>();
+        HashSet<Integer> b = new HashSet<>();
+        int n = sc.nextInt(), m = sc.nextInt();
+        for(int i=0;i<n;i++){
+            a.add(sc.nextInt());
+        }
+        for(int i=0;i<m;i++){
+            b.add(sc.nextInt());
+        }
+        a.forEach(k -> h.add(k));
+        b.forEach(k -> h.add(k));
+        h.forEach((k)->{
+            System.out.printf("%d ", k);
+        });
+        sc.close();
+    }
+}

J02007 - ĐẾM SỐ LẦN XUẤT HIỆN.java

@@ -0,0 +1,31 @@
+import java.util.Scanner;
+import java.util.Map;
+import java.util.HashMap;
+
+public class Main {
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        for(int j=1;j<=t;j++){
+            System.out.printf("Test %d:\n",j);
+            int n=sc.nextInt();
+            int[] a = new int[n];
+            for(int i=0;i<n;i++){
+                a[i]=sc.nextInt();
+            }
+            Map<Integer,Integer> m = new HashMap<Integer,Integer>();
+            for(int i=0;i<n;i++){
+                if(m.get(a[i]) == null){
+                    m.put(a[i], 1);
+                }else m.put(a[i], m.get(a[i])+1);
+            }
+            for(int i=0;i<n;i++){
+                if(m.get(a[i])>0){
+                    System.out.printf("%d xuat hien %d lan\n",a[i],m.get(a[i]));
+                    m.put(a[i], 0);
+                }
+            }
+        }
+        sc.close();
+    }
+}

J02008 - BỘI SỐ NHỎ NHẤT CỦA N SỐ NGUYÊN DƯƠNG ĐẦU TIÊN.java

@@ -0,0 +1,24 @@
+import java.util.Scanner;
+
+public class Main {
+    static long gcd(long a,long b){
+        if(b==0) return a;
+        return gcd(b,a%b);
+    }
+    static long lcm(long a,long b){
+        return a*b/gcd(a,b);
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        while(t-->0){
+            long n=sc.nextLong();
+            long s=1;
+            for(int i=1;i<=n;i++){
+                s=lcm(s,i);
+            }
+            System.out.println(s);
+        }
+        sc.close();
+    }
+}

J02009 - XẾP HÀNG.java

@@ -0,0 +1,28 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static class pair{
+        public int first, second;
+        public pair(int a, int b){
+            first = a;
+            second = b;
+        }
+    }
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        ArrayList<pair> a = new ArrayList<>(); 
+        for(int i=0;i<n;i++) a.add(new pair(sc.nextInt(), sc.nextInt()));
+        a.sort((pair x, pair b) -> {
+            return x.first - b.first;
+        });
+        int now = 0;
+        for(int i=0;i<n;i++){
+            if(a.get(i).first>=now) now=a.get(i).first+a.get(i).second;
+            else now+=a.get(i).second;
+        }
+        System.out.println(now);
+    }
+}

J02010 - SẮP XẾP ĐỔI CHỖ TRỰC TIẾP.java

@@ -0,0 +1,34 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+   
+    static void out(int[] a, int n, int step){
+        System.out.printf("Buoc %d: ",step);
+        for(int i=0;i<n;i++){
+           System.out.printf("%d ", a[i]);
+        }
+        System.out.println("");
+    }
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int[] a = new int[n];
+        for(int i=0;i<n;i++){
+            a[i] = sc.nextInt();
+        }
+        for(int i=0;i<n-1;i++){
+            for(int j=i+1;j<n;j++){
+                if (a[i]>a[j]) {
+                    int tmp = a[i];
+                    a[i] = a[j];
+                    a[j] = tmp;
+                }
+            }
+            out(a,n,i+1);
+        }
+        sc.close();
+    }
+}

J02011 - SẮP XẾP CHỌN.java

@@ -0,0 +1,36 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+   
+    static void out(int[] a, int n, int step){
+        System.out.printf("Buoc %d: ",step);
+        for(int i=0;i<n;i++){
+           System.out.printf("%d ", a[i]);
+        }
+        System.out.println("");
+    }
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int[] a = new int[n];
+        for(int i=0;i<n;i++){
+            a[i] = sc.nextInt();
+        }
+        for(int i=0;i<n-1;i++){
+            int candindex = i;
+            for(int j=i+1;j<n;j++){
+                if (a[candindex]>a[j]) {
+                    candindex=j;
+                }
+            }
+            int tmp = a[i];
+            a[i] = a[candindex];
+            a[candindex] = tmp;
+            out(a,n,i+1);
+        }
+        sc.close();
+    }
+}

J02012 - SẮP XẾP CHÈN.java

@@ -0,0 +1,27 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.ArrayList;
+import java.util.Collections;
+
+public class test{
+   
+    static void out(ArrayList<Integer> a, int step){
+        System.out.printf("Buoc %d: ", step);
+        a.forEach(k -> System.out.printf("%d ", k));
+        System.out.println("");
+    }
+    
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        ArrayList<Integer> a = new ArrayList<>();
+        for(int i=0;i<n;i++){
+            a.add(sc.nextInt());
+            Collections.sort(a);
+            out(a,i);
+        }
+        sc.close();
+    }
+}

J02013 - SẮP XẾP NỔI BỌT.java

@@ -0,0 +1,44 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.ArrayList;
+import java.util.Collections;
+
+public class test{
+   
+    static void out(int[] a, int n, int step){
+        System.out.printf("Buoc %d: ", step);
+        for(int i=0;i<n;i++){
+            System.out.printf("%d ", a[i]);
+        }
+        System.out.println("");
+    }
+    
+    static boolean isSorted(int[] a, int n){
+        for(int i=0;i<n-1;i++){
+            if(a[i]>a[i+1]) return false;
+        }
+        return true;
+    }
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int[] a = new int[n];
+        for(int i=0;i<n;i++){
+            a[i] = sc.nextInt();
+        }
+        for(int i=0;i<n-1;i++){
+            for(int j=0;j<n-1;j++){
+                if(a[j]>a[j+1]){
+                    int tmp = a[j];
+                    a[j] = a[j+1];
+                    a[j+1] = tmp;
+                }
+            }
+            out(a,n,i+1);
+            if(isSorted(a,n)) break;
+        }
+        sc.close();
+    }
+}

J02014 - ĐIỂM CÂN BẰNG.java

@@ -0,0 +1,29 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt();
+            int[] a = new int[n+1];
+            for(int i=1;i<n+1;i++){
+                a[i] = sc.nextInt();
+                a[i]+=a[i-1];
+            }
+            boolean oke = true;
+            for(int i=2;i<n;i++){
+                if(a[i-1]==(a[n]-a[i])){
+                    System.out.println(i);
+                    oke = false;
+                    break;
+                }
+            }
+            if(oke) System.out.println(-1);
+        }
+        sc.close();
+    }
+}

J02016 - BỘ BA SỐ PYTAGO.java

@@ -0,0 +1,33 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static boolean check(long[] a){
+        for(int i=a.length-1;i>=2;i--){
+            int j=0, k=i-1;
+            while(j<k){
+                long x = a[j] + a[k];
+                if (x==a[i]) return true;
+                if(x>a[i]) k--;
+                else j++;
+            }
+        }
+        return false;
+    }
+    static long sq(Long x){
+        return x*x;
+    }
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt();
+            long[] a = new long[n];
+            for (int i = 0; i < n; i++)
+                a[i] = sq(sc.nextLong());
+            if(check(a)) System.out.println("YES");
+            else System.out.println("NO");
+        }
+    }
+}

J02017 - THU GỌN DÃY SỐ.java

@@ -0,0 +1,23 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.Stack;
+
+public class test{
+    
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        Stack<Integer> a = new Stack<>();
+        for(int i=0; i<n; i++){
+            int x = sc.nextInt();
+            if(a.empty()) a.push(x);
+            else{
+                if((a.lastElement()+x)%2==0) a.pop();
+                else a.push(x);
+            }
+        }
+        System.out.print(a.size());
+        sc.close();
+    }
+}

J02019 - TỔNG ƯỚC SỐ - 2.java

@@ -0,0 +1,40 @@
+
+import java.util.Scanner;
+public class non {
+
+    static int N = 1000000;
+    static int[] U = new int[N+2];
+    static int pow(int a, int b){
+        if(b==0) return 1;
+        if(b%2==1) return pow(a,b-1)*a;
+        int p = pow(a, b>>1);
+        return p*p;
+    }
+    static void set(){
+        for(int i=2;i<=(int)Math.sqrt(N);++i){
+            if(U[i]==0){
+                U[i]=i;
+                for(int j=0;j<=N/i;++j) U[i*j] = i;
+            }
+        }
+        for(int i=2;i<=N;++i){
+            if(U[i]==0) U[i]=i+1;
+            else{
+                int n = i, x = 0;
+                while(n%U[i]==0){
+                    n/=U[i];
+                    x++;
+                }
+                if(n==1) U[i] = (pow(U[i], x+1) - 1)/(U[i]-1);
+                else U[i] = U[pow(U[i], x)] * U[n];
+            }
+        }
+    }
+    public static void main(String[] args) {
+        set();
+        Scanner sc = new Scanner(System.in);
+        int a = sc.nextInt(), b = sc.nextInt(), cnt = 0;
+        for(int i=a;i<=b;++i) if(U[i] - i > i) ++cnt;
+        System.out.println(cnt);
+    }
+}

J02020 - LIỆT KÊ TỔ HỢP - 1.java

@@ -0,0 +1,30 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.Stack;
+
+public class test{
+    static int n, k, cnt=0;
+    static void Try(int i, int start, int[] res){
+        if(i==k){
+            cnt++;
+            for(int j=0; j<k; j++){
+                System.out.printf("%d ",res[j]);
+            }
+            System.out.println("");
+            return;
+        }
+        for(int u=start; u<=n-k+i+1 ; u++){
+            res[i]=u;
+            Try(i+1,u+1,res);
+        }
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        n = sc.nextInt(); k = sc.nextInt();
+        int[] res = new int[k];
+        Try(0,1,res);
+        System.out.printf("Tong cong co %d to hop", cnt);
+        sc.close();
+    }
+}

J02021 - LIỆT KÊ TỔ HỢP - 2.java

@@ -0,0 +1,30 @@
+package nyagami;
+
+import java.util.Scanner;
+import java.util.Stack;
+
+public class test{
+    static int n, k, cnt=0;
+    static void Try(int i, int start, int[] res){
+        if(i==k){
+            cnt++;
+            for(int j=0; j<k; j++){
+                System.out.print(res[j]);
+            }
+            System.out.print(" ");
+            return;
+        }
+        for(int u=start; u<=n-k+i+1 ; u++){
+            res[i]=u;
+            Try(i+1,u+1,res);
+        }
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        n = sc.nextInt(); k = sc.nextInt();
+        int[] res = new int[k];
+        Try(0,1,res);
+        System.out.printf("\nTong cong co %d to hop", cnt);
+        sc.close();
+    }
+}

J02022 - SỐ XA CÁCH.java

@@ -0,0 +1,36 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    static int n;
+    static void Try(int i,int[] a, boolean[] vs){
+        if(i==n){
+            for(int j=0; j<n; j++){
+                System.out.print(a[j]);
+            }
+            System.out.println("");
+            return;
+        }
+        for(int j=1; j<=n; j++){
+            if(!vs[j] && (i==0 || (i>0 && Math.abs(j-a[i-1])!=1))){
+                vs[j]=true;
+                a[i]=j;
+                Try(i+1,a,vs);
+                vs[j]=false;
+            }
+        }
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            n = sc.nextInt();
+            boolean[] visited = new boolean[n+1];
+            int[] a = new int[n];
+            Try(0,a,visited);
+            System.out.println("");
+        }
+        sc.close();
+    }
+}

J02023 - LỰA CHỌN THAM LAM.java

@@ -0,0 +1,29 @@
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt(), s = sc.nextInt(), n9 = 0;
+        String Max = "", Min = "";
+        if(n*9 < s || s == 0){
+            System.out.println("-1 -1");
+            return;
+        }
+        while(s>=9){
+            Max += "9";
+            n9++;
+            s-=9;
+        }
+        if(s!=0) Max += Integer.toString(s);
+        while(Max.length()<n) Max+="0";
+        if(n9 != n && s == 0){
+            n9--;
+            s=9;
+        }
+        if(s!=0 && n9+1 != n) System.out.print("1");
+        for(int i=0;i<n-n9-(s>0?2:0);i++) System.out.print("0");
+        if(s>0) System.out.print(n9+1!=n?s-1:s);
+        while(n9-->0) System.out.print("9");
+        System.out.printf(" %s",Max);
+    }
+}

J02024 - DÃY CON CÓ TỔNG LẺ.java

@@ -0,0 +1,41 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static ArrayList<String> ans;
+
+    static void Try(int end, int[] a, int sum, String s) {
+        if (sum % 2 == 1) {
+            System.out.println(s);
+            ans.add(s);
+        }
+        for (int i = a.length - 1; i > end; i--) {
+            Try(i, a, sum + a[i], s + a[i] + ' ');
+        }
+    }
+
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            int n = sc.nextInt();
+            int[] a = new int[n];
+            ans = new ArrayList<>();
+            for (int i = 0; i < n; i++)
+                a[i] = sc.nextInt();
+            for (int i = 0; i < n - 1; i++) {
+                for (int j = i + 1; j < n; j++) {
+                    if (a[i] < a[j]) {
+                        int tmp = a[i];
+                        a[i] = a[j];
+                        a[j] = tmp;
+                    }
+                }
+            }
+            Try(-1, a, 0, "");
+            Collections.sort(ans);
+            // ans.forEach(e -> System.out.println(e));
+        }
+    }
+}

J02025 - DÃY CON CÓ TỔNG NGUYÊN TỐ.java

@@ -0,0 +1,47 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static boolean primr(int x) {
+        if (x < 2)
+            return false;
+        if (x == 2)
+            return true;
+        if (x % 2 == 0)
+            return false;
+        for (int i = 3; i <= (int) Math.sqrt(x); i += 2) {
+            if (x % i == 0)
+                return false;
+
+        }
+        return true;
+    }
+    static void Try(int end, int[] a, int sum, String s) {
+        if (primr(sum)) System.out.println(s);
+        for (int i = a.length - 1; i > end; i--) {
+            Try(i, a, sum + a[i], s + a[i] + ' ');
+        }
+    }
+
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            int n = sc.nextInt();
+            int[] a = new int[n];
+            for (int i = 0; i < n; i++)
+                a[i] = sc.nextInt();
+            for (int i = 0; i < n - 1; i++) {
+                for (int j = i + 1; j < n; j++) {
+                    if (a[i] < a[j]) {
+                        int tmp = a[i];
+                        a[i] = a[j];
+                        a[j] = tmp;
+                    }
+                }
+            }
+            Try(-1, a, 0, "");
+        }
+    }
+}

J02026 - DÃY CON CÓ K PHẦN TỬ TĂNG DẦN.java

@@ -0,0 +1,26 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static void Try(int start, int cnt, int k, int[] a, String s){
+        if(cnt==k){
+            System.out.println(s);
+            return;
+        }
+        for(int i=start; i<a.length;i++){
+            Try(i+1, cnt+1, k, a, s+a[i]+' ');
+        }
+    }
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt(), k = sc.nextInt();
+            int[] a = new int[n];
+            for(int i=0;i<n;i++) a[i]=sc.nextInt();
+            Arrays.sort(a);
+            Try(0,0,k,a,"");
+        }
+    }
+}

J02027 - KHOẢNG CÁCH NHỎ HƠN K.java

@@ -0,0 +1,28 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static int uppper_bound(int l, int r, int[] a, int x){
+        if(l>r) return l;
+        int mid = (l+r)/2;
+        if(a[mid] > x) return uppper_bound(l, mid - 1 , a, x);
+        return uppper_bound(mid + 1, r, a, x);
+    }
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt(), k = sc.nextInt();
+            int[] a = new int[n];
+            for(int i=0;i<n;i++) a[i]=sc.nextInt();
+            Arrays.sort(a);
+            long sum = 0;
+            for(int i=1;i<n;i++){
+                int index = uppper_bound(0, i-1, a, a[i]-k);
+                sum += (long)(i - index);
+            }
+            System.out.println(sum);
+        }
+    }
+}

J02028 - DÃY CON LIÊN TIẾP TỔNG BẰNG K.java

@@ -0,0 +1,35 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt();
+            long k = sc.nextLong();
+            long[] a = new long[n];
+            for(int i=0;i<n;i++) a[i] = sc.nextLong();
+            int l = 0, r = 0;
+            long sum = a[l];
+            boolean check = false;
+            while(l<n){
+                if(sum == k){
+                    check = true;
+                    break;
+                }
+                if(l==r || sum < k){
+                    r++;
+                    if(r==n) break;
+                    sum+=a[r];
+                }else if(sum > k){
+                    sum-=a[l];
+                    l++;
+                }
+            }
+            if(check) System.out.println("YES");
+            else System.out.println("NO");
+        }
+    }
+}

J02033 - ĐẢO DẤU.java

@@ -0,0 +1,28 @@
+import java.io.*;
+import java.util.*;
+
+public class non {
+
+    public static void main(String[] args) throws IOException {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        long k = sc.nextLong();
+        long[] a = new long[n];
+        for(int i=0;i<n;i++) a[i] = sc.nextLong();
+        Arrays.sort(a);
+        int cntn = 0;
+        for(long i:a) if(i<0) cntn++;
+        long sum = 0;
+        if(k<=cntn){
+            for(int i=0;i<k;i++) a[i] = -a[i];
+        }else{
+            for(int i=0;i<cntn;i++) a[i] = -a[i];
+            Arrays.sort(a);
+            k-=cntn;
+            if(k%2==1) a[0] = -a[0];
+        }
+        for(long i:a) sum+=i;
+        System.out.println(sum);
+    }
+}
+

J02034 - BỔ SUNG DÃY SỐ.java

@@ -0,0 +1,27 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int last = 0;
+        int cnt = 0;
+        for(int i=0; i<n; i++){
+            int x = sc.nextInt();
+            if(x==last+1){
+                last=x;
+                continue;
+            }else{
+                cnt++;
+                for(int j=last+1; j<x; j++){
+                    System.out.println(j);
+                }
+                last=x;
+            }
+        }
+        if(cnt==0) System.out.println("Excellent!");
+        sc.close();
+    }
+}

J02035 - QUAY PHẢI.java

@@ -0,0 +1,23 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt();
+            int[] a = new int[n];
+            int[] b = new int[n];
+            for(int i=0;i<n;i++) b[i] = a[i] = sc.nextInt();
+            Arrays.sort(a);
+            for(int i=0;i<n;i++){
+                if(b[i] == a[0]){
+                    System.out.println(i);
+                    break;
+                }
+            }
+        }
+    }
+}

J020356 - LỰA CHỌN THAM LAM.java

@@ -0,0 +1,29 @@
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt(), s = sc.nextInt(), n9 = 0;
+        String Max = "";
+        if(n*9 < s || s == 0){
+            System.out.println("-1 -1");
+            return;
+        }
+        while(s>=9){
+            Max += "9";
+            n9++;
+            s-=9;
+        }
+        if(s!=0) Max += Integer.toString(s);
+        while(Max.length()<n) Max+="0";
+        if(n9 != n && s == 0){
+            n9--;
+            s=9;
+        }
+        if(s!=0 && n9+1 != n) System.out.print("1");
+        for(int i=0;i<n-n9-(s>0?2:0);i++) System.out.print("0");
+        if(s>0) System.out.print(n9+1!=n?s-1:s);
+        while(n9-->0) System.out.print("9");
+        System.out.printf(" %s",Max);
+    }
+}

J02036 - ƯỚC SỐ CHUNG LỚN NHẤT.java

@@ -0,0 +1,33 @@
+import java.util.*;
+
+public class Main {
+    static int gcd(int a, int b) {
+        if (b == 0)
+            return a;
+        return gcd(b, a % b);
+    }
+
+    static int lcm(int a, int b) {
+        return a * b / gcd(a, b);
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            int n = sc.nextInt();
+            int[] a = new int[n];
+            int[] b = new int[n + 1];
+            for (int i = 0; i < n; i++)
+                a[i] = sc.nextInt();
+            b[0] = a[0];
+            for (int i = 1; i < n; i++) {
+                b[i] = lcm(a[i], a[i - 1]);
+            }
+            b[n] = a[n - 1];
+            for (int i = 0; i < n + 1; i++) {
+                System.out.printf("%d ", b[i]);
+            }
+            System.out.println();
+        }
+    }
+}

J02037 - DÃY ƯU THẾ.java

@@ -0,0 +1,22 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    public static void main(String[] args) throws IOException, ClassNotFoundException {
+        // Scanner sc = new Scanner(new File("ONLINE.in"));
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        sc.nextLine();
+        while (t-- > 0) {
+            String[] s = sc.nextLine().trim().split("\\s+");
+            int cnt = 0;
+            for (int i = 0; i < s.length; i++) {
+                if (Integer.parseInt(s[i]) % 2 == 0)
+                    cnt++;
+            }
+            if (s.length % 2 == 0 && cnt > s.length - cnt || s.length % 2 == 1 && s.length - cnt > cnt)
+                System.out.println("YES");
+            else System.out.println("NO");
+        }
+    }
+}

J02101 - IN MA TRẬN.java

@@ -0,0 +1,29 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            int n = sc.nextInt();
+            int[][] a = new int[n][n];
+            for(int i=0; i<n; i++){
+                for(int j=0; j<n; j++) a[i][j] = sc.nextInt();
+            }
+            int j = 0;
+            for(int i=0; i<n; i++){
+                if(j==0){
+                    for(; j<n; j++) System.out.printf("%d ", a[i][j]);
+                    j=n-1;
+                }else{
+                    for(; j>=0; j--) System.out.printf("%d ", a[i][j]);
+                    j=0;
+                }
+            }
+            System.out.println("");
+        }
+        sc.close();
+    }
+}

J02102 - MA TRẬN XOẮN ỐC TĂNG DẦN.java

@@ -0,0 +1,50 @@
+import java.util.*;
+
+public class Main {
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int[][] a = new int[n][n];
+        int[] b = new int[n * n];
+        for (int i = 0; i < n * n; i++)
+            b[i] = sc.nextInt();
+        Arrays.sort(b);
+        int x = 0, y = 0, i = 0;
+        while (i < n * n) {
+            while (y < n && a[x][y] == 0) {
+                a[x][y] = b[i];
+                y++;
+                i++;
+            }
+            x++;
+            y--;
+            while (x < n && a[x][y] == 0) {
+                a[x][y] = b[i];
+                x++;
+                i++;
+            }
+            y--;
+            x--;
+            while (y >= 0 && a[x][y] == 0) {
+                a[x][y] = b[i];
+                y--;
+                i++;
+            }
+            x--;
+            y++;
+            while (x >= 0 && a[x][y] == 0) {
+                a[x][y] = b[i];
+                x--;
+                i++;
+            }
+            y++;
+            x++;
+        }
+        for (i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                System.out.printf("%d ", a[i][j]);
+            }
+            System.out.println("");
+        }
+    }
+}

J02103 - TÍCH MA TRẬN VỚI CHUYỂN VỊ CỦA NÓ.java

@@ -0,0 +1,45 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+    static int[][] trans(int[][] a, int n, int m){
+        int[][] b = new int[m][n];
+        for(int i=0; i<m; i++){
+            for(int j=0; j<n; j++) b[i][j] = a[j][i];
+        }
+        return b;
+    }
+    static int[][] mul(int[][] a, int[][]b, int n, int m){
+        int res[][] = new int[n][n];
+        for(int i=0; i<n; i++){
+            for(int j=0; j<n; j++){
+                int sum = 0;
+                for(int k=0; k<m; k++) sum+=a[i][k]*b[k][j];
+                res[i][j] = sum;
+            }
+        }
+        return res;
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        for(int ts=1; ts<=t; ts++){
+            int n = sc.nextInt(), m = sc.nextInt();
+            int[][] a = new int[n][m];
+            for(int i=0; i<n; i++){
+                for(int j=0; j<m; j++) a[i][j] = sc.nextInt();
+            }
+            int[][] b = trans(a, n, m);
+            int[][] res = mul(a, b, n, m);
+            System.out.printf("Test %d:\n", ts);
+            for(int i=0; i<n; i++){
+                for(int j=0; j<n; j++){
+                    System.out.printf("%d ", res[i][j]);
+                }
+                System.out.println("");
+            }
+        }
+        sc.close();
+    }
+}

J02104 - DANH SÁCH CẠNH.java

@@ -0,0 +1,21 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        for(int i=1; i<=n; i++){
+            for(int j=1; j<=n; j++){
+                int x = sc.nextInt();
+                if(x==1 && i<j){
+                    System.out.printf("(%d,%d)\n", i, j);
+                }
+            } 
+        }
+        
+        sc.close();
+    }
+}

J02105 - DANH SÁCH KỀ.java

@@ -0,0 +1,21 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        for(int i=1; i<=n; i++){
+            System.out.printf("List(%d) = ", i);
+            for(int j=1; j<=n; j++){
+                int x = sc.nextInt();
+                if(x==1) System.out.printf("%d ", j);
+            } 
+            System.out.println("");
+        }
+        
+        sc.close();
+    }
+}

J02106 - MA TRẬN NHỊ PHÂN.java

@@ -0,0 +1,19 @@
+package nyagami;
+
+import java.util.Scanner;
+
+public class test{
+
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int res = 0;
+        for(int i=1; i<=n; i++){
+            int cnt = 0;
+            for(int j=1; j<=3; j++) cnt+=sc.nextInt();
+            if(cnt > 3-cnt) res++;
+        }
+        System.out.print(res);
+        sc.close();
+    }
+}

J03004 - CHUẨN HÓA XÂU HỌ TÊN - 1.java

@@ -0,0 +1,33 @@
+package pkg1.chuan_hoa_xau_ho_ten1;
+
+import java.util.Scanner;
+
+
+public class Chuan_hoa_xau_ho_ten1 {
+    
+    static String edit(String s){
+        String s1 = s.substring(0, 1);
+        String s2 = s.substring(1, s.length());
+        s1 = s1.toUpperCase();
+        return s1+s2;
+    }
+    
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        sc.nextLine();
+        while(t>0){
+            t-=1;
+            String s = sc.nextLine();
+            s = s.toLowerCase();
+            s = s.replaceAll("\\s+", " ");
+            s = s.trim();       
+            String word[] = s.split("\\s");
+            for( String i : word){
+                System.out.print(edit(i)+" ");
+            }
+            System.out.println("");
+        }
+    }
+    
+}

J03005 - CHUẨN HÓA XÂU HỌ TÊN - 2.java

@@ -0,0 +1,35 @@
+import java.util.Scanner;
+import java.util.ArrayDeque;
+import java.util.Queue;
+
+public class Main{
+    static char up(char x){
+        if('a'<=x && x<='z') return (char)((int)x-32);
+        return x;
+    }
+    static Queue<String> re(String name){
+        String[] a = name.split("[' ']+");
+        Queue<String> r = new ArrayDeque<>();
+    
+        for(int i=0; i<a.length; i++){
+            if(a[i].length() == 0) continue;
+            String s = Character.toString(up(a[i].charAt(0))) + a[i].substring(1);
+            r.add(s);
+        }
+        return r;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        while(sc.hasNextLine()){
+            String name = sc.nextLine();
+            if(name.length() == 0) continue;
+            Queue<String> q = re(name.toLowerCase());
+            String[] a = new String[q.size()];
+            q.toArray(a);
+            a[a.length-1] += ",";
+            for(int i=1; i<a.length; i++) System.out.printf("%s ",a[i]);
+            System.out.println(a[0].toUpperCase());
+        }
+    }
+}

J03006 - SỐ ĐẸP 1.java

@@ -0,0 +1,22 @@
+import java.util.Scanner;
+
+public class Main {
+    static String check(String s){
+        int n=s.length();
+        for(int i=0;i<n;i++){
+            char x=s.charAt(i),y=s.charAt(n-i-1);
+            if(x!=y) return "NO";
+            if((x-'0')%2==1) return "NO";
+        }
+        return "YES";
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        while(t-->0){
+            String s=sc.next();
+            System.out.println(check(s));
+        }
+        sc.close();
+    }
+}

J03007 - SỐ ĐẸP 2.java

@@ -0,0 +1,23 @@
+import java.util.Scanner;
+
+public class Main {
+    static String check(String s){
+        int n=s.length();
+        if(s.charAt(n-1)!='8') return "NO";
+        int sum=0;
+        for(int i=0;i<n;i++){
+            sum+=s.charAt(i)-'0';
+        }
+        if(sum%10!=0) return "NO";
+        return "YES";
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        while(t-->0){
+            String s=sc.next();
+            System.out.println(check(s));
+        }
+        sc.close();
+    }
+}

J03008 - SỐ ĐẸP 3.java

@@ -0,0 +1,22 @@
+import java.util.Scanner;
+
+public class Main {
+    static String nt="2357";
+    static String check(String s){
+        int n=s.length();
+        for(int i=0;i<n;i++){
+            if(nt.indexOf(s.charAt(i))==-1) return "NO";
+            if(s.charAt(i)!=s.charAt(n-1-i)) return "NO";
+        }
+        return "YES";
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        while(t-->0){
+            String s=sc.next();
+            System.out.println(check(s));
+        }
+        sc.close();
+    }
+}

J03009 - TẬP TỪ RIÊNG CỦA HAI XÂU.java

@@ -0,0 +1,37 @@
+/*
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Main.java to edit this template
+ */
+package pkg6.tap_tu_rieng_cua_2_xau;
+
+import java.util.HashSet;
+import java.util.Scanner;
+import java.util.Set;
+
+/**
+ *
+ * @author GIGABYTE
+ */
+public class Tap_tu_rieng_cua_2_xau {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        sc.nextLine();
+        while(t>0){
+            t-=1;
+            Set<String> st = new HashSet<>();
+            String s1[] = sc.nextLine().split("\\s");
+            String s2 = sc.nextLine();
+            for(String word: s1){
+                if(!s2.contains(word)){
+                    st.add(word);
+                }
+            }
+            for(String i: st){
+                System.out.print(i + " ");
+            }
+            System.out.println("");
+        }
+    }
+    
+}

J03010 - ĐỊA CHỈ EMAIL.java

@@ -0,0 +1,31 @@
+import java.util.Scanner;
+import java.util.HashMap;
+
+public class Main{
+    static String mail(String s){
+        String[] a = s.split("[' ']+");
+        String r = a[a.length-1];
+        for(int i=0; i<a.length-1; i++){
+            if(a[i].length() != 0) r += Character.toString(a[i].charAt(0));
+        }
+        return r;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        sc.next();
+        HashMap<String, Integer> a = new HashMap<>();
+        while(sc.hasNextLine()){
+            String name = sc.nextLine();
+            if(name.length() == 0) continue;
+            String user = mail(name.toLowerCase());
+            if(a.get(user) == null){
+                a.put(user, 2);
+            }else{
+                int th = a.get(user);
+                a.put(user, th+1);
+                user += Integer.toString(th);
+            }
+            System.out.println(user + "@ptit.edu.vn");
+        }
+    }
+}

J03011 - ƯỚC SỐ CHUNG LỚN NHẤT CỦA SỐ NGUYÊN LỚN.java

@@ -0,0 +1,18 @@
+import java.math.BigInteger;
+import java.util.Scanner;
+
+public class Main {
+    static BigInteger gcd(BigInteger a, BigInteger b){
+        if(b.equals(BigInteger.ZERO)) return a;
+        return gcd(b,a.mod(b));
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        while(t-->0){
+            BigInteger a=sc.nextBigInteger(), b=sc.nextBigInteger();
+            System.out.println(gcd(a,b));
+        }
+        sc.close();
+    }
+}

J03012 - TỔNG SỐ NGUYÊN LỚN - 1.java

@@ -0,0 +1,13 @@
+import java.util.*;
+import java.math.*;
+public class Main {
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            BigInteger a = new BigInteger(sc.next());
+            BigInteger b = new BigInteger(sc.next());
+            System.out.println(a.add(b));
+        }
+    }
+}

J03013 - HIỆU SỐ NGUYÊN LỚN - 1.java

@@ -0,0 +1,17 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main{
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            BigInteger a = new BigInteger(sc.next());
+            BigInteger b = new BigInteger(sc.next());
+            int max = Math.max(a.toString().length(), b.toString().length());
+            String ans = a.subtract(b).abs().toString();
+            while(ans.length()<max) ans = "0" + ans;
+            System.out.println(ans);
+        }
+    }
+}

J03014 - TỔNG SỐ NGUYÊN LỚN - 2.java

@@ -0,0 +1,13 @@
+import java.util.*;
+import java.math.*;
+public class Main {
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t = 1;
+        while(t-->0){
+            BigInteger a = new BigInteger(sc.next());
+            BigInteger b = new BigInteger(sc.next());
+            System.out.println(a.add(b));
+        }
+    }
+}

J03015 - HIỆU SỐ NGUYÊN LỚN - 2.java

@@ -0,0 +1,14 @@
+import java.math.BigInteger;
+import java.util.Scanner;
+
+public class Main {
+    static BigInteger gcd(BigInteger a, BigInteger b){
+        if(b.equals(BigInteger.ZERO)) return a;
+        return gcd(b,a.mod(b));
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        BigInteger a=sc.nextBigInteger(),b=sc.nextBigInteger();
+        System.out.println(a.subtract(b));
+    }
+}

J03016 - CHIA HẾT CHO 11.java

@@ -0,0 +1,14 @@
+import java.util.*;
+import java.math.*;
+public class Main {
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            BigInteger a = new BigInteger(sc.next());
+            if (a.mod(new BigInteger("11")).equals(BigInteger.ZERO))
+                System.out.println("1");
+            else System.out.println("0");
+        }
+    }
+}

J03017 - LOẠI BỎ “100”.java

@@ -0,0 +1,33 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = Integer.parseInt(sc.nextLine());
+        while(t-->0){
+            String s = sc.next();
+            Stack<Integer> st = new Stack<>();
+            for(int i=0;i<s.length();i++){
+                if(st.size()<2) st.push(i);
+                else{
+                    if(s.charAt(i) == '0' && s.charAt(st.lastElement()) == '0' && s.charAt(st.elementAt(st.size() - 2)) == '1'){
+                        st.pop();
+                        st.pop();
+                    }else st.push(i);
+                }
+            }
+            int ans = 0;
+            for(int i=1;i<st.size();i++){
+                ans = Math.max(ans, st.elementAt(i) - st.elementAt(i-1) - 1);
+            }
+            if(st.empty()) ans = s.length();
+            else{
+                ans = Math.max(ans, st.elementAt(0));
+                ans = Math.max(ans, s.length() - st.lastElement() - 1);
+            }
+            System.out.println(ans);
+        }
+    }
+}

J03018 - TÌM SỐ DƯ.java

@@ -0,0 +1,22 @@
+import java.math.*;
+import java.util.*;
+
+public class Main {
+
+    static int pow(int a, int b) {
+        if (b == 0)
+            return 1;
+        return a * pow(a, b - 1);
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            BigInteger n = new BigInteger(sc.next());
+            int a = Integer.parseInt(n.mod(BigInteger.valueOf(4)).toString());
+            int b = Integer.parseInt(n.mod(BigInteger.valueOf(2)).toString());
+            int s = 1 + pow(2, a) + pow(3, a) + pow(4, b);
+            System.out.println(s%5);
+        }
+    }
+}

J03019 - XÂU CON LỚN NHẤT.java

@@ -0,0 +1,31 @@
+import java.util.*;
+import java.math.*;
+
+public class Main {
+    static class pi {
+        char c;
+        int index;
+
+        public pi(char x, int y) {
+            c = x;
+            index = y;
+        }
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        String s = sc.next();
+        ArrayList<pi> a = new ArrayList<>();
+        for (int i = 0; i < s.length(); i++)
+            a.add(new pi(s.charAt(i), i));
+        a.sort((pi x, pi y) -> {
+            return (int) (y.c - x.c);
+        });
+        int pre = 0;
+        for (int i = 0; i < a.size(); i++) {
+            if (a.get(i).index < pre)
+                continue;
+            System.out.print(a.get(i).c);
+            pre = a.get(i).index;
+        }
+    }
+}

J03020 - TÌM TỪ THUẬN NGHỊCH DÀI NHẤT.java

@@ -0,0 +1,61 @@
+import java.util.*;
+
+public class Main {
+    
+    static class word {
+        String w;
+        int cnt, stt;
+
+        public word(String w, int i) {
+            this.w = w;
+            this.cnt = 1;
+            this.stt = i;
+        }
+
+        @Override
+        public String toString() {
+            return w + " " + cnt;
+        }
+    }
+
+    static boolean tn(String s) {
+        for (int i = 0; i < s.length() / 2; i++) {
+            if (s.charAt(i) != s.charAt(s.length() - 1 - i))
+                return false;
+        }
+        return true;
+    }
+
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        ArrayList<word> a = new ArrayList<>();
+        int index = 0;
+        while (sc.hasNext()) {
+            String s = sc.next();
+            if (!tn(s))
+                continue;
+            boolean oke = true;
+            for (int i = 0; i < a.size(); i++) {
+                if (a.get(i).w.compareTo(s) == 0) {
+                    oke = false;
+                    a.get(i).cnt += 1;
+                }
+            }
+            if (oke) {
+                a.add(new word(s, index));
+                index++;
+            }
+        }
+        a.sort((word x, word y) -> {
+            if (x.w.length() == y.w.length()) {
+                return x.stt - y.stt;
+            }
+            return y.w.length() - x.w.length();
+        });
+        a.forEach(e -> {
+            if (e.w.length() == a.get(0).w.length())
+                System.out.println(e);
+        });
+    }
+}

J03021 - ĐIỆN THOẠI CỤC GẠCH.java

@@ -0,0 +1,35 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main{
+    static char convert(char x){
+        if("ABC".indexOf(x) > -1) return '2';
+        if("DEF".indexOf(x) > -1) return '3';
+        if("GHI".indexOf(x) > -1) return '4';
+        if("JKL".indexOf(x) > -1) return '5';
+        if("MNO".indexOf(x) > -1) return '6';
+        if("PQRS".indexOf(x) > -1) return '7';
+        if("TUV".indexOf(x) > -1) return '8';
+        return '9';
+    }
+    static boolean dx(char[] a, int n){
+        for(int i=0;i<=n/2;i++){
+            if(a[i]!=a[n-i-1]) return false;
+        }
+        return true;
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            String s = sc.next();
+            s = s.toUpperCase();
+            char[] c = new char[s.length()];
+            for(int i=0; i<s.length(); i++){
+                c[i] = convert(s.charAt(i));
+            }
+            if(dx(c, c.length)) System.out.println("YES");
+            else System.out.println("NO");
+        }
+    }
+}

J03022 - XỬ LÝ VĂN BẢN.java

@@ -0,0 +1,19 @@
+import java.util.*;
+
+public class Main {
+
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        String s = "";
+        while (sc.hasNextLine())
+            s += sc.nextLine();
+        String[] a = s.trim().toLowerCase().split("[.?!]");
+        for (String i : a) {
+            i = i.trim();
+            i = Character.toString(i.charAt(0)).toUpperCase() + i.substring(1);
+            for (String j : i.split("\\s+"))
+                System.out.printf("%s ", j);
+            System.out.println("");
+        }
+    }
+}

J03023 - SỐ LA MÃ.java

@@ -0,0 +1,30 @@
+import java.util.*;
+
+public class Main {
+    static HashMap<Character, Integer> a = new HashMap<>();
+    static String LM = "MDCLXVI";
+
+    static int cal(String s) {
+        for (int i = 0; i < LM.length(); i++) {
+            if (s.indexOf(LM.charAt(i)) > -1) {
+                int x = s.indexOf(LM.charAt(i));
+                return a.get(LM.charAt(i)) - cal(s.substring(0, x)) + cal(s.substring(x + 1));
+            }
+        }
+        return 0;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        a.put('I', 1);
+        a.put('V', 5);
+        a.put('X', 10);
+        a.put('L', 50);
+        a.put('C', 100);
+        a.put('D', 500);
+        a.put('M', 1000);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            System.out.println(cal(sc.next()));
+        }
+    }
+}

J03024 - SỐ ƯU THẾ.java

@@ -0,0 +1,29 @@
+import java.math.BigInteger;
+import java.util.Scanner;
+
+public class Main {
+    static boolean is(char x){
+        if(x>='0' && x<='9') return true;
+        return false;
+    }
+    static String check(String s){
+        if(s.charAt(0)=='0') return "INVALID";
+        int n=s.length();
+        int c=0;
+        for(int i=0;i<n;i++){
+            if(!is(s.charAt(i))) return "INVALID";
+            if((s.charAt(i)-'0')%2==0) c++;
+        }
+        if(n%2==0 && c>n-c) return "YES";
+        if(n%2==1 && c<n-c) return "YES";
+        return "NO";
+    }
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t=sc.nextInt();
+        for(int i=0;i<t;i++){
+            System.out.println(check(sc.next()));
+        }
+        sc.close(); 
+    }
+}

J03025 - XÂU ĐỐI XỨNG.java

@@ -0,0 +1,18 @@
+import java.util.Scanner;
+
+public class Main{
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            String S = sc.next();
+            int cnt = 0;
+            for(int i=0; i<S.length()/2; i++){
+                if(S.charAt(i) != S.charAt(S.length()-i-1)) cnt++;
+            }
+            if(cnt==1 || cnt==0 && S.length() % 2 == 1) System.out.println("YES");
+            else System.out.println("NO");
+        }
+        sc.close();
+    }
+}

J03026 - XÂU KHÁC NHAU DÀI NHẤT.java

@@ -0,0 +1,22 @@
+import java.util.Scanner;
+
+public class Main{
+    static boolean eq(String a, String b){
+        if(a.length() != b.length()) return false;
+        for(int i=0; i<a.length(); i++){
+            if(a.charAt(i) != b.charAt(i)) return false;
+        }
+        return true;
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            String a = sc.next();
+            String b = sc.next();
+            if(!eq(a,b)) System.out.println(Math.max(a.length(), b.length()));
+            else System.out.println("-1");
+        }
+        sc.close();
+    }
+}

J03027 - RÚT GỌN XÂU KÝ TỰ.java

@@ -0,0 +1,20 @@
+import java.util.Scanner;
+import java.util.Stack;
+
+public class Main{
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        String s = sc.next();
+        Stack<Character> a = new Stack<>();
+        for(int i=0; i<s.length(); i++){
+            if(a.empty()) a.push(s.charAt(i));
+            else{
+                if(a.lastElement() == s.charAt(i)) a.pop();
+                else a.push(s.charAt(i));
+            }
+        }
+        if(a.empty()) System.out.println("Empty String");
+        else a.forEach(c -> System.out.print(c));
+        sc.close();
+    }
+}

J03028 - MÃ HÓA DRM.java

@@ -0,0 +1,37 @@
+import java.util.*;
+public class non {
+
+    static int value(String s){
+        int cnt = 0;
+        for(int i=0; i<s.length(); i++){
+            cnt += (int)(s.charAt(i)-'A');
+        }
+        return cnt;
+    }
+
+    static String turn(String s){
+        int value = value(s);
+        String r = "";
+        for(int i=0;i<s.length();i++){
+            r += (char)((s.charAt(i) - 'A' + value)%26 + 'A');
+        }
+        return r;
+    }
+
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            String s = sc.next();
+            String a = s.substring(0, s.length()/2);
+            String b = s.substring(s.length()/2);
+            a = turn(a);
+            b = turn(b);
+            String r = "";
+            for(int i=0;i<a.length();i++){
+                r += (char)((a.charAt(i) + b.charAt(i) - 2*'A')%26 + 'A');
+            }
+            System.out.println(r);
+        }
+    }
+}

J03029 - CHUẨN HÓA CÂU.java

@@ -0,0 +1,36 @@
+
+import java.util.Scanner;
+public class non {
+    static String deli = ".!?";
+    static void process(String s){
+        if(s.length() == 0) return;
+        if(deli.indexOf(s.charAt(s.length()-1)) == -1){
+            s += ".";
+        }
+        String a[] = s.split("\\s+");
+        int n = a.length;
+        if(a[a.length - 1].length() == 1 && deli.contains(a[a.length - 1])){
+            if(a.length>1){
+                n-=1;
+                a[a.length - 2] += a[a.length - 1];
+            }
+        }
+        int i=0;
+        while(i<n){
+            a[i] = Character.toString(a[i].charAt(0)).toUpperCase() + a[i].substring(1);
+            while(deli.indexOf(a[i].charAt(a[i].length()-1)) == -1){
+                System.out.printf("%s ", a[i]);
+                i++;
+            }
+            System.out.printf("%s ", a[i]);
+            i++;
+            System.out.println();
+        }
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        while(sc.hasNextLine()){
+            process(sc.nextLine().toLowerCase().trim());
+        }
+    }
+}

J03030 - BIẾN ĐỔI A – B.java

@@ -0,0 +1,25 @@
+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package nxt;
+import java.util.Scanner;
+public class App {
+    public static void main(String[] args) {
+        Scanner sc=new Scanner(System.in);
+        String s = sc.next();
+        int n = s.length();
+        int[] dpA = new int[n+1];
+        int[] dpB = new int[n+1];
+        for(int i=1; i<=n; i++){
+            if(s.charAt(i-1)=='A'){
+                dpA[i]=Math.min(dpA[i-1],dpB[i-1]+1);
+                dpB[i]=Math.min(dpB[i-1]+1, dpA[i-1]+1);
+            }else{
+                dpA[i]=Math.min(dpA[i-1]+1,dpB[i-1]+1);
+                dpB[i]=Math.min(dpB[i-1], dpA[i-1]+1);
+            }
+        }
+        System.out.print(dpA[n]);
+        sc.close();
+    }
+}

J03031 - XÂU ĐẦY ĐỦ.java

@@ -0,0 +1,18 @@
+import java.util.*;
+public class Main {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while (t-- > 0) {
+            String s = sc.next();
+            int k = sc.nextInt();
+            HashSet<Character> hs = new HashSet<>();
+            for (int i = 0; i < s.length(); i++) {
+                hs.add(s.charAt(i));
+            }
+            if (s.length() >= 26 && hs.size() + k >= 26) {
+                System.out.println("YES");
+            }else System.out.println("NO");
+        }
+    }
+}

J03032 - ĐẢO TỪ.java

@@ -0,0 +1,22 @@
+import java.util.Scanner;
+import java.util.Stack;
+
+public class Main{
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        sc.nextLine();
+        while(t-->0){
+            String line = sc.nextLine();
+            String[] w = line.split("[' ']+");
+            for(int i=0; i<w.length; i++){
+                for(int j=0; j<w[i].length(); j++){
+                    System.out.print(w[i].charAt(w[i].length()-j-1));
+                }
+                System.out.print(' ');
+            }
+            System.out.println("");
+        }
+        sc.close();
+    }
+}

J03033 - BỘI SỐ CHUNG NHỎ NHẤT.java

@@ -0,0 +1,19 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main{
+    static BigInteger gcd(BigInteger a, BigInteger b){
+        if(b.equals(BigInteger.ZERO)) return a;
+        return gcd(b, a.mod(b));
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            BigInteger a = new BigInteger(sc.next());
+            BigInteger b = new BigInteger(sc.next());
+            System.out.println(a.multiply(b).divide(gcd(a,b)));
+        }
+        sc.close();
+    }
+}

J03035 - ĐIỀN CHỮ SỐ.java

@@ -0,0 +1,46 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    
+    static long pow(long a, long b){
+        if(b==0) return 1;
+        return pow(a, b-1) * a;
+    }
+
+    static long q_cnt(String a){
+        long r=0;
+        for(int i=0;i<a.length();i++){
+            if(a.charAt(i) == '?') r++;
+        }
+        return r;
+    }
+
+    static long cnt(int i, String a, String b, long rm){
+        if(i==a.length()) return 0;
+        if(a.charAt(i)=='?'){
+            return (long)('9' - b.charAt(i))*pow(10, rm - 1) + cnt(i+1, a, b, rm - 1);
+        }
+        else{
+            if(a.charAt(i) < b.charAt(i)) return 0;
+            if(a.charAt(i) > b.charAt(i)) return pow(10, rm);
+            return cnt(i+1, a, b, rm);
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = Integer.parseInt(sc.nextLine());
+        while(t-->0){
+            String a = sc.next(), b = sc.next();
+            long n = q_cnt(a);
+            if(a.length()<b.length() || n==0) System.out.println(0);
+            else if(a.length() > b.length()){
+                if(a.charAt(0) == '?') System.out.println(9*pow(10, n-1));
+                else System.out.println(pow(10, n));
+            }else{
+                System.out.println(cnt(0,a,b,n));
+            }
+        }
+    }
+}

J03036 - XOAY VÒNG KÝ TỰ.java

@@ -0,0 +1,39 @@
+import java.util.*;
+
+public class non {
+
+    static int turn(String a, String b){
+        if(a.length() != b.length()) return -1;
+        String s = a;
+        for(int i=0;i<=a.length();i++){
+            if(s.compareTo(b) == 0) return i;
+            s = s.substring(1) + s.charAt(0);
+        }
+        return -1;
+    }
+
+    static void solve(String[] a){
+        int ans = 1000000;
+        for(String i: a){
+            int cnt = 0;
+            for(String j:a){   
+                int x = turn(j, i);
+                if(x==-1){
+                    System.out.println(-1);
+                    return;
+                }
+                cnt+=x;
+            }
+            ans=Math.min(ans, cnt);
+        }
+        System.out.println(ans);
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        String[] a = new String[n];
+        for(int i=0;i<a.length;i++) a[i] = sc.next();
+        solve(a);
+    }
+}

J03037 - VÒNG TRÒN.java

@@ -0,0 +1,35 @@
+import java.util.*;
+
+public class Main {
+    static class pair {
+        int x, y;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        String s = sc.next();
+        ArrayList<pair> a = new ArrayList<>();
+        for (char c = 'A'; c <= 'Z'; c++) {
+            int i = 0;
+            pair x = new pair();
+            for (int j = 0; j < s.length(); j++) {
+                if (s.charAt(j) == c) {
+                    if (i == 0) {
+                        x.x = j;
+                        i++;
+                    } else
+                        x.y = j;
+                }
+            }
+            a.add(x);
+        }
+        int cnt = 0;
+        for (int i = 0; i < a.size() - 1; i++) {
+            for (int j = i + 1; j < a.size(); j++) {
+                if (a.get(i).y < a.get(j).x || a.get(j).y < a.get(i).x || (a.get(i).x-a.get(j).x) * (a.get(j).y -a.get(i).y) > 0)
+                    continue;
+                cnt++;
+            }
+        }
+        System.out.println(cnt);
+    }
+}

J03038 - ĐÁNH DẤU CHỮ CÁI.java

@@ -0,0 +1,34 @@
+/*
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
+ * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Main.java to edit this template
+ */
+package pkg17.danh_dau_chu_cai;
+
+import java.util.HashSet;
+import java.util.Scanner;
+import java.util.Set;
+
+/**
+ *
+ * @author GIGABYTE
+ */
+public class Danh_dau_chu_cai {
+
+    /**
+     * @param args the command line arguments
+     */
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        
+           
+            String s = sc.nextLine();
+            Set<String> st = new HashSet<>();
+            for(int i=0;i<s.length();i++){
+                String temp = s.charAt(i)+" ";
+                st.add(temp);
+            }
+            System.out.println(st.size());
+        
+    }
+    
+}

J03039 - CHIA HẾT.java

@@ -0,0 +1,16 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main{
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            BigInteger a = new BigInteger(sc.next());
+            BigInteger b = new BigInteger(sc.next());
+            if(a.mod(b).equals(BigInteger.ZERO) || b.mod(a).equals(BigInteger.ZERO)) System.out.println("YES");
+            else System.out.println("NO");
+        }
+        sc.close();
+    }
+}

J03040 - BIỂN SỐ ĐẸP.java

@@ -0,0 +1,32 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main{
+    static boolean inc(String s){
+        for(int i=0; i<s.length()-1; i++){
+            if(s.charAt(i) >= s.charAt(i+1)) return false;
+        }
+        return true;
+    }
+    static boolean equal(String s){
+        if(s.charAt(0) == s.charAt(1) && s.charAt(1) == s.charAt(2) && s.charAt(3) == s.charAt(4)) return true;
+        return false;
+    }
+    static boolean se(String s){
+        for(int i=0; i<s.length(); i++){
+            if("68".indexOf(s.charAt(i)) == -1) return false;
+        }
+        return true;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-->0){
+            String card = sc.next().substring(5);
+            String[] a = card.split("['.']");
+            card = a[0] + a[1];
+            if(inc(card) || equal(card) || se(card)) System.out.println("YES");
+            else System.out.println("NO");
+        }
+    }
+}

J04001 - KHAI BÁO LỚP POINT.java

@@ -0,0 +1,25 @@
+import java.util.Scanner;
+public class Main{
+    static class point{
+        double x,y;
+        public void get(Scanner sc){
+            x = sc.nextDouble();
+            y = sc.nextDouble();
+        }
+    }
+    static double dis(point a, point b){
+        return Math.sqrt(Math.pow(a.x-b.x,2) + Math.pow(a.y - b.y, 2));
+    }
+    public static void main(String args[]){
+        Scanner sc = new Scanner(System.in);
+        int t = sc.nextInt();
+        while(t-- > 0){
+            point a = new point(); 
+            point b = new point();
+            a.get(sc);
+            b.get(sc);
+            System.out.printf("%.4f\n",dis(a,b));
+        }
+        sc.close();
+    }
+}

J04002 - KHAI BÁO LỚP HÌNH CHỮ NHẬT.java

@@ -0,0 +1,17 @@
+import java.util.Scanner;
+import java.math.BigInteger;
+
+public class Main{
+    static String st(String s){
+        if(s.length()==1) return "" + Character.toUpperCase(s.charAt(0));
+        s = s.toLowerCase();
+        return "" + Character.toUpperCase(s.charAt(0)) + s.substring(1);
+    }
+    public static void main(String[] arg){
+        Scanner sc = new Scanner(System.in);
+        int a = sc.nextInt(), b = sc.nextInt();
+        String c = sc.next();
+        if(a>0 && b>0) System.out.printf("%d %d %s",(a+b)*2, a*b, st(c));
+        else System.out.println("INVALID");
+    }
+}