CF621B 模拟

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;int d[5678];struct point{    int x;    int y;}p[200005];int dia[5678],ddia[5678];//储存对角线上的鲨鱼数量int main(){    int n;    scanf("%d",&n);    for(int i=0;i<n;i++){        scanf("%d%d",&p[i].x,&p[i].y);        dia[p[i].x+p[i].y-1]++;        ddia[1000+p[i].x-p[i].y]++;    }    long long sum=0;    for(int i=0;i<=2000;i++){        sum+=dia[i]*(dia[i]-1)/2;        sum+=ddia[i]*(ddia[i]-1)/2;    }    printf("%I64d\n",sum);    return 0;}