激光炸弹

#include <bits/stdc++.h>
using namespace std;

const int N = 5100;

int v[N][N];

int l, r;

void solve(){
    int n, k; cin >> n >> k;
    k = min(k, 5001);
    l = r = k;  //初始边界
    for(int i = 1; i <= n; i ++){
        int a, b, c; cin >> a >> b >> c;
        v[a + 1][b + 1] += c;
        l = max(a + 1, l), r = max(b + 1, r);  //更新边界
    }
    for(int i = 1; i <= l; i ++){
        for(int j = 1; j <= r; j ++){
            v[i][j] += v[i - 1][j] + v[i][j - 1] - v[i - 1][j - 1];  //二维前缀和
        }
    }
    int res = 0;
    for(int i = k; i <= l; i ++){
        for(int j = k; j <= r; j ++){
            res = max(res, v[i][j] - v[i - k][j] - v[i][j - k] + v[i - k][j - k]);
        }
    }
    cout << res << endl;
}

int main(){
    solve();
    return 0;
}