dp--poj1050，最大子矩阵

#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <iomanip>
#include <cstdio>

using namespace std;
typedef long long LL;
typedef pair<double, double> PDD;
typedef pair<LL, LL> PLL;

const LL N = 127+50;
const LL MOD = 1e9+7;
const LL INF = 0x3f3f3f3f;

#define lson l, m, rt>>1
#define rson m+1, r, rt>>1|1

LL dp[N][N], n, ans;
LL a[N];
void solve()
{
    for(int i = 1;i <= n;++i)//行
    {
        memset(a, 0, sizeof(a));
        for(int j = i;j <= n;++j)//行
        {
            for(int k = 1;k <= n;++k)//列
                a[k] += dp[j][k];
            LL sum = 0;
            for(int k = 1;k <= n;++k)//一维最长连续子序列
            {
                sum += a[k];
                if(sum < 0) sum = 0;
                else ans = max(ans, sum);
            }
        }
    }
    cout << ans << endl;
}

int main()
{
    scanf("%lld", &n);
    for(int i = 1;i <= n;++i)
        for(int j = 1;j <= n;++j)
        scanf("%lld", &dp[i][j]);
    solve();
    return 0;
}