CodeForces 621B Wet Shark and Bishops

记录一下每个对角线上有几个，然后就可以算了

#include<cstdio>
#include<cstring>
#include<cmath>
#include<ctime>
#include<vector>
#include<algorithm>
using namespace std;

const int maxn=+;
int n;
long long w1[maxn];
long long w2[maxn];
long long ans;

int main()
{
    int n;
    scanf("%d",&n);
    ans=;
    memset(w1,,sizeof w1);
    memset(w2,,sizeof w2);

    for(int i=; i<=n; i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        int p=;

        p=p+(x-);
        p=p-(y-);

        w1[p]++;

        p=;
        p=p+x-;
        p=p-(-y);
        w2[p]++;
    }

    for(int i=; i<=; i++)
        if(w1[i]!=&&w1[i]!=)
            ans=ans+(w1[i]-)*w1[i]/;

    for(int i=; i<=; i++)
        if(w2[i]!=&&w2[i]!=)
            ans=ans+(w2[i]-)*w2[i]/;

    printf("%lld\n",ans);

    return ;
}