1598D - Training Session - CodeForces Solution

#include<bits/stdc++.h>
#define ll long long
using namespace std;

void solve(){ 
	ll n;
	cin>>n;
	vector<pair<ll,ll>> v(n);
	map<ll,ll> mp1,mp2;
	for(ll i = 0;i<n;i++){
		cin>>v[i].first>>v[i].second;
		mp1[v[i].first]++;
		mp2[v[i].second]++;
	}
	ll total = (n * (n-1)*(n-2))/6;
	for(ll i = 0;i<n;i++){
		total -= (mp1[v[i].first]-1) * (mp2[v[i].second]-1); 
	}
	cout<<total<<endl;
}
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	int t;
	cin>>t;
	while(t--) solve();
}