51nod 1158 全是1的最大子矩阵

题目链接：51nod 1158 全是1的最大子矩阵

题目分类是单调栈，我这里直接用与解最大子矩阵类似的办法水过了。。。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#define CLR(a,b) memset((a),(b),sizeof((a)))
using namespace std;
const int N = 501;
const int inf = 0x3f3f3f3f;
int n, m;
int dp[N][N];
int main(){
    int i, j, k, ans, x, h;
    scanf("%d%d", &m, &n);
    CLR(dp, 0);
    for(i = 1; i <= n; ++i){
        for(j = 1; j <= m; ++j){
            scanf("%d", &x);
            if(x) dp[i][j] = x + dp[i-1][j];
        }
    }
    ans = 0;
    for(i = 1; i <= m; ++i){
        for(j = 1 ; j <= n; ++j){
            h = inf;
            for(k = i; k <= m; ++k){
                h = min(h, dp[j][k]);
                if(h == 0) break;
                ans = max(ans, (k-i+1) * h);
            }
        }
    }
    printf("%d
", ans);
    return 0;
}