洛谷 P2004 领地选择

题目传送门

解题思路:

二维前缀和.

AC代码:

 #include<iostream>
 #include<cstdio>

 using namespace std;

 int n,m,c,g[][],ansi = ,ansj = ;
 long long a[][],k[][],ans = -;
 //ans一定要初始化,-9999999都不行 

 int main() {
     scanf("%d%d%d",&n,&m,&c);
     for(int i = ;i <= n; i++)
         for(int j = ;j <= m; j++)
             scanf("%d",&g[i][j]);
     for(int i = ;i <= n; i++)
         for(int j = ;j <= m; j++) {
             a[i][j] = a[i-][j] + a[i][j-] - a[i-][j-] + g[i][j];
             if(i >= c && j >= c) {
                 k[i][j] = a[i][j] - a[i-c][j] - a[i][j-c] + a[i-c][j-c];
                 if(k[i][j] > ans) {
                     ans = k[i][j];
                     ansi = i - c + ;
                     ansj = j - c + ;
                 }
             }
         }
     printf("%d %d",ansi,ansj);
     return ;
 }