PROG-1077: กุญแจ (key)

#include <bits/stdc++.h>
using namespace std;
int ar[1010][1010];
int main(){
    int n,m;
    scanf("%d %d",&n,&m);
    for(int i=0;i<n;i++){
        int x,y;
        scanf("%d %d",&x,&y);
        x++;
        y++;
        ar[x][y]++;
    }
    for(int i=1;i<=1001;i++){
        for(int j=1;j<=1001;j++){
            ar[i][j]=ar[i][j]+ar[i-1][j]+ar[i][j-1]-ar[i-1][j-1];
        }
    }
    while(m--){
        int x,y,k,x1,y1,x2,y2;
        scanf("%d %d %d",&x,&y,&k);
        x++;
        y++;
        x1=x-k;
        y1=y-k;
        x2=x+k;
        y2=y+k;
        if(x1<1) x1=1;
        if(y1<1) y1=1;
        if(x2<1) x2=1;
        if(y2<1) y2=1;
        if(x2>1001) x2=1001;
        if(y2>1001) y2=1001;
        printf("%d\n",ar[x2][y2]-ar[x1-1][y2]-ar[x2][y1-1]+ar[x1-1][y1-1]);
    }
    return 0;
}