HDU 1081 To The Max

#include <cstdio>
#include <climits>
#include <algorithm>
#include <cstring>

using namespace std;

const int maxn = 105;
const int INF = INT_MAX / 2;

int sum[maxn][maxn],v[maxn][maxn],t[maxn];

int maxsum(int *f,int n) {
    int ans = -INF,now = -INF;
    for(int i = 1;i <= n;i++) {
        now = max(now + f[i],f[i]);
        ans = max(ans,now);
    }
    return ans;
}

int main() {
    int n;
    while(~scanf("%d",&n)) {
        int ans = -INF;
        for(int i = 1;i <= n;i++) {
            for(int j = 1;j <= n;j++) {
                scanf("%d",&v[i][j]);
                sum[i][j] = sum[i - 1][j] + v[i][j];
            }
        }
        for(int j = 1;j <= n;j++) {
            for(int k = j + 1;k <= n;k++) {
                for(int i = 1;i <= n;i++) {
                    t[i] = sum[k][i] - sum[j - 1][i];
                }
                ans = max(ans,maxsum(t,n));
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}