Submission #530921

#	Time	Username	Problem	Language	Result	Execution time	Memory
530921		ohohorz	Star triangles (IZhO11_triangle)	C++14	0 / 100	239 ms	20400 KiB

triangle

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define f first
#define s second
#define mp make_pair
#define pb push_back


const int N = 1e5 + 5;
const int INF = 1e18;
int x[N], y[N];
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);

    int n;
    cin>>n;    
    int ans = 0;
    for(int i = 1;i <= n;i++){
        cin >> x[i] >> y[i];
    }
    set< pii> se;

    map<int,int> cntx, cnty;
    map<pii, int> lol;
    for(int i= 1;i <= n;i++){
        cntx[x[i]] ++;
        cnty[y[i]] ++;
        lol[mp(x[i], y[i])] ++;
    }



    for(int i = 1;i <= n;i++){
        // if(se.count(mp(x[i], y[i]))) continue;
        int a = x[i], b = y[i];
        
        // (a, b2)
        // (a, b)   (a2, b)

        // find number of points such that x = a
        // find number of points such that y = b
        ans += ((cntx[a] - 1) * (cnty[b] - 1));
        se.insert(mp(a, b));
    }
    cout <<ans<<"\n";

}

• Subtask 1: 0 / 100