最大子矩阵和 URAL 1146 Maximum Sum

题目传送门

/*
    最大子矩阵和：把二维降到一维，即把列压缩；然后看是否满足最大连续子序列；
    好像之前做过，没印象了，看来做过的题目要经常看看:)
*/
#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;

const int MAXN = 1e2 + 10;
const int INF = 0x3f3f3f3f;
int a[MAXN][MAXN];
int dp[MAXN][MAXN][MAXN];

int main(void)        //URAL 1146 Maximum Sum
{
    //freopen ("D.in", "r", stdin);

    int n;
    while (scanf ("%d", &n) == 1)
    {
        int ans = -INF;
        memset (dp, 0, sizeof (dp));
        for (int i=1; i<=n; ++i)
        {
            for (int j=1; j<=n; ++j)
            {
                scanf ("%d", &a[i][j]);
            }
        }

        for (int i=1; i<=n; ++i)
        {
            for (int j=1; j<=n; ++j)
            {
                int sum = 0;
                for (int k=j; k>=1; --k)
                {
                    sum += a[i][k];
                    dp[i][j][k] = max (sum + dp[i-1][j][k], sum);
                    ans = max (ans, dp[i][j][k]);
                }
            }
        }

        printf ("%d
", ans);
    }

    return 0;
}