题解 | #最大子矩阵#

import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[][] a = new int[n + 1][n + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                a[i][j] = in.nextInt();
            }
        }
        int[][] sum = new int[n + 1][n + 1];
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                sum[i][j] = sum[i - 1][j] + a[i][j];
            }
        }
        int maxSum = Integer.MIN_VALUE;
        for (int i = 1; i <= n; i++) {
            for (int j = i; j <= n; j++) {
                int[] dp = new int[n + 1];
                for (int  k = 1; k <= n; k++) {
                    int x = sum[j][k] - sum[i - 1][k];
                    dp[k] = Math.max(x + dp[k - 1], x);
                    maxSum = Math.max(maxSum, dp[k]);
                }
            }
        }
        System.out.println(maxSum);
    }
}

二维前缀和+二维数组dp