first commit

J08023 - HÌNH CHỮ NHẬT LỚN NHẤT.java

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+import java.util.*;
+
+public class non {
+
+    static void min(long[] a, int[] b, int start, int end, int step, int root){
+        Stack<Integer> st = new Stack<>();
+        for(int i=start;i!=end;i+=step){
+            while(!st.isEmpty() && a[st.lastElement()] >= a[i]) st.pop();
+            if(st.isEmpty()) b[i] = root;
+            else b[i] = st.lastElement();
+            st.push(i);
+        }
+    }
+    public static void main(String[] args) {
+        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] = sc.nextLong();
+            int[] l = new int[n];
+            int[] r = new int[n];
+            min(a, l, 0, n, 1, -1);
+            min(a, r, n-1, -1, -1, n);
+            long ans = 0;
+            for(int i=0;i<n;i++){
+                ans = Math.max(ans, a[i]*(r[i]-l[i]-1));
+            }
+            System.out.println(ans);
+        }
+    }
+}