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

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

         printf ("%d\n", ans);
     }

     return ;
 }