제출 #154392

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
154392		srvlt	Star triangles (IZhO11_triangle)	C++14	0 / 100	2 ms	376 KiB

triangle

//#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#define ll long long
#define db long double
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define fi first
#define se second
#define mp make_pair
#define endl "\n"
#define int long long
using namespace std;

void dout() {
    cerr << endl;
}

template <typename Head, typename... Tail>
void dout(Head H, Tail... T) {
    cerr << H << ' ';
    dout(T...);
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef pair <int, int> pii;
const int N = 3e5 + 3;
int n, ans;
vector <pii> v;
map <pii, int> q;
map <int, int> x, y;

void solve(int tc) {
    cin >> n;
    for (int i = 0; i < n; i++) {
        pii p;
        cin >> p.fi >> p.se;
        v.pb(p);
    }
    sort(v.begin(), v.end());
    for (int i = 0; i < n; i++) {
        x[v[i].fi]++;
        y[v[i].se]++;
        q[v[i]]++;
    }
    for (int i = 0; i < n; i++) {
        ans += x[v[i].fi] * y[v[i].se] - 2 * q[v[i]];
    }
    assert(ans % 2 == 0);
    cout << ans / 2;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);
    int tc = 1;
//    cin >> tc;
    for (int i = 0; i < tc; i++) {
        solve(i);
//        cleanup();
    }
}

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