Acwing-99- laser bombs (prefix and two-dimensional)

link:

https://www.acwing.com/problem/content/101/

Meaning of the questions:

A novel laser bombs that can destroy all of the length of one side of the square R of the target.

There are N target on the map, with integer Xi, Yi represents the position of the target on the map, and each has a target value Wi.

Laser bombs served by satellite positioning, but it has a disadvantage that its explosion range, i.e., the side length of the sides of the square must R and x, y-axis.

If the target is located on the edge of the square blasting, the target will not be destroyed.

Seeking a bomb blew up on the map up to a total value of how much of the target.

Ideas:

Dimensional prefix and do it, then violence can be.

Code:

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
const int MAXN = 5e3+10;

int Sum[MAXN][MAXN];
int n, r;

int main()
{
    scanf("%d%d", &n, &r);
    int x, y, v;
    int maxx = r, maxy = r;
    for (int i = 1;i <= n;i++)
    {
        scanf("%d%d%d", &x, &y, &v);
        x++, y++;
        Sum[x][y] = v;
        maxx = max(maxx, x);
        maxy = max(maxy, y);
    }
    for (int i = 1;i <= maxx;i++)
    {
        for (int j = 1;j <= maxy;j++)
            Sum[i][j] = Sum[i-1][j]+Sum[i][j-1]-Sum[i-1][j-1]+Sum[i][j];
    }
    int res = 0;
    for (int i = r;i <= maxx;i++)
    {
        for (int j = r;j <= maxy;j++)
        {
            res = max(res, Sum[i][j]-Sum[i][j-r]-Sum[i-r][j]+Sum[i-r][j-r]);
        }
    }
    printf("%lld\n", res);

    return 0;
}