first commit

J03019 - XÂU CON LỚN NHẤT.java

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+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;
+        }
+    }
+}