蓝桥杯最大子矩阵c++

以下是一个求解最大子矩阵的C语言代码，使用动态规划算法：

#include <stdio.h>
#include <stdlib.h>

#define MAX_N 1000

int max(int a, int b) {
    return a > b ? a : b;
}

int main() {
    int n, m, a[MAX_N][MAX_N], f[MAX_N][MAX_N], ans = 0;
    scanf("%d %d", &n, &m);
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            scanf("%d", &a[i][j]);
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (j == 0) {
                f[i][j] = a[i][j];
            } else {
                f[i][j] = a[i][j] ? f[i][j - 1] + 1 : 0;
            }
        }
    }
    for (int j = 0; j < m; j++) {
        int h[MAX_N], stk[MAX_N], top = -1;
        for (int i = 0; i < n; i++) {
            h[i] = f[i][j];
            while (top >= 0 && h[stk[top]] >= h[i]) {
                int k = stk[top--];
                int l = top >= 0 ? stk[top] : -1;
                ans = max(ans, h[k] * (i - l - 1));
            }
            stk[++top] = i;
        }
        while (top >= 0) {
            int k = stk[top--];
            int l = top >= 0 ? stk[top] : -1;
            ans = max(ans, h[k] * (n - l - 1));
        }
    }
    printf("%d\n", ans);
    return 0;
}

该算法的时间复杂度为$O(nm)$，空间复杂度为$O(nm)$。