题解 | #最大矩形面积#

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Stack;

public class Main {

public static void main(String[] args) throws IOException {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    String s = br.readLine();

    String[] str = br.readLine().split(" ");

    int n = Integer.parseInt(s);

    int[] a = new int[n];

    for (int i = 0; i < n; i++) {

        a[i] = Integer.parseInt(str[i]);//写入数组

    }

    int max = 0, maxArea = 0;

    for (int i = 0; i < n; i++) {//两次循环从左向右依次算出每块图形面积

        int min = Integer.MAX_VALUE;

        for (int j = i; j < n; j++) {

            if (a[j] < min) {

                min = a[j];

            }

            max = min * (j + 1 - i);

            if (max > maxArea) {

                maxArea = max;

            }

        }

    }

    System.out.print(maxArea);

}

}