[luoguP2280] [HNOI2003]激光炸弹（DP）

传送门

二位前缀和DP大水题

——代码

 #include <cstdio>
 #include <iostream>

 const int MAXN = ;
 int n, r, ans;
 int sum[MAXN][MAXN];

 inline int read()
 {
     int x = , f = ;
     char ch = getchar();
     for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -;
     for(; isdigit(ch); ch = getchar()) x = (x << ) + (x << ) + ch - '';
     return x * f;
 }

 inline int max(int x, int y)
 {
     return x > y ? x : y;
 }

 int main()
 {
     int i, j, x, y, z;
     n = read();
     r = read();
     for(i = ; i <= n; i++)
     {
         x = read();
         y = read();
         sum[x + ][y + ] = read();
     }
     for(i = ; i <= ; i++)
         for(j = ; j <= ; j++)
             sum[i][j] += sum[i - ][j] + sum[i][j - ] - sum[i - ][j - ];
     for(i = r; i <= ; i++)
         for(j = r; j <= ; j++)
             ans = max(ans, sum[i][j] - sum[i - r][j] - sum[i][j - r] + sum[i - r][j - r]);
     printf("%d\n", ans);
     return ;
 }