激光炸弹（二维前缀和）

枚举正方行边长为r的

#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;

const int N = 5e3 + 5;
int g[N][N];
int main(){
    int N,R;
    cin >> N >> R;
    int n = R, m = R;
    for(int i = 0, x, y, w; i < N; ++ i)
    {
        cin >> x >> y >> w;
        x++,y++;
        n = max(x,n), m = max(m, y);
        g[x][y] += w;
    }
    for(int i = 1; i <= n; ++ i)//求前缀和 
        for(int j = 1; j <= m; ++ j)
            g[i][j] += g[i-1][j] + g[i][j-1] - g[i-1][j-1];
    int ans = 0;
    for(int i = R; i <= n; ++ i)
        for(int j = R; j <= m; ++ j)
            ans = max(ans, g[i][j] - g[i-R][j] - g[i][j-R] + g[i-R][j-R]);//枚举正方形 
    cout << ans << endl;
    return 0;
}