title: 激光炸弹
date: 2023-12-14 19:42:59
tags: 前缀和
categories: 算法进阶指南

题目链接

$-->$ 传送门

题目大意

思路

代码

#include<bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz size()
#define bpt __builtin_popcountll

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> PII;

const int N = 5e3 +10, mod = 1e9 + 7;

int g[N][N];

int main()
{
    int n,R;
    cin >> n >> R;
    R = min(R,5001);
    for(int i = 1; i <= n;  i++){
        int x,y,c;
        cin >> x >> y >> c;
        g[++x][++y] += c;
    }
    
    for(int i = 1; i <= 5001; i ++){
        for(int j = 1; j <= 5001; j ++){
            g[i][j] = g[i-1][j] +g[i][j - 1] - g[i-1][j-1] + g[i][j];
        }
    }
    
    int ans = 0;
    for(int i = R ; i <= 5001; i ++){
        for(int j  = R ; j <= 5001; j ++){
            ans = max(ans,g[i][j] - g[i-R][j] - g[i][j - R] + g[i - R][j - R]);
        }
    }
    cout << ans << endl;
    return 0;
}