hdu 1559 最大子矩阵 (简单dp)

题目：http://acm.hdu.edu.cn/showproblem.php?pid=1559

 #include <cstring>
 #include <cstdlib>
 #include <cstdio>
 #include <iostream>
 #include <algorithm>
 using namespace std;
 const int maxn = +;
 const int INF = <<;
 int map[maxn][maxn];  //表示以[1,1]为左上角，以[i,j]为右下角的矩形的和

 int main()
 {
     int t, i, j, m, n, x, y;
     int s1, sc, Max, ans;
     scanf("%d", &t);
     while(t--)
     {
         memset(map, , sizeof(map));
         Max = -INF;
         scanf("%d%d%d%d", &m, &n, &x, &y);
         for(i = ; i <= m; i++)
         {
             s1 = ;
             for(j = ; j <= n; j++)
             {
                 scanf("%d", &sc);
                 s1 += sc;
                 map[i][j] = s1+map[i-][j];
             }
         }
         for(i = ; i <= m; i++)
             for(j = ; j <= n; j++)
                 if((i+x-)<=m && (j+y-)<=n)
                 {
                     ans = map[i+x-][j+y-]-map[i+x-][j-]-map[i-][j+y-]+map[i-][j-];//减出来就是以[i,j]
                     //为左顶点，大小为xy的矩形的和
                     if(Max < ans)
                         Max = ans;
                 }
         printf("%d\n", Max);
     }
     return ;
 }