poj 1050(DP)

最大子矩阵和。类似于子序列最大和。

// File Name: 1050.cpp
// Author: Missa_Chen
// Created Time: 2013年06月22日 星期六 17时06分39秒

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

using namespace std;

#define LL long long
const int inf = 0x3f3f3f3f;
const int maxn = 101;
int n;
int sum[maxn][maxn];
int main()
{
    while (~scanf("%d",&n))
    {
        for (int i = 1; i <= n; ++i)
            for (int j = 1; j <= n; ++j)
                scanf("%d", &sum[i][j]);
        for (int i = 1; i <= n; ++i)
            sum[i][0] = 0;
        for (int i = 1; i <= n; ++i)
            for (int j = 2; j <= n; ++j)
                sum[i][j] += sum[i][j - 1];
        int ans = -inf;
        for (int i = 1; i <= n; ++i)
            for (int j = i; j <= n; ++j)
            {
                int tmp = -inf;
                for (int k = 1; k <= n; ++k)
                {
                    if (tmp >= 0)
                        tmp += (sum[k][j] - sum[k][i - 1]);
                    else
                        tmp = sum[k][j] - sum[k][i - 1];
                    ans = max(ans, tmp);
                }
            }
        printf("%d
", ans);
    }
    return 0;
}