Submission #1129675

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129675		zhasyn	Star triangles (IZhO11_triangle)	C++20	0 / 100	6 ms	7496 KiB

triangle

#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
using namespace std;
#define F first
#define S second
typedef long long ll;
#define pii pair <int, int>
#define pll pair <ll, ll>
typedef long double ld;
const ll N = 3 * 1e5 + 100, M = 500 + 10, len = 315, inf = 1e18;
const ll mod = 998244353;
ll um(ll a, ll b){
	return (1LL * a * b) % mod;
}
ll subr(ll a, ll b){
	return ((1LL * a - b) % mod + mod) % mod;
}
ll bp(ll x, ll step){
	ll res = 1;
	while(step){
		if(step & 1) res = um(res, x);
		x = um(x, x);
		step /= 2;
	}
	return res;
}
ll inv(ll x){
	return bp(x, mod - 2);
}
ll a[N], b[N], ax[N], bx[N], cnt[N];
vector <ll> in[N];
int main() {
	//ios_base::sync_with_stdio(false);
	//cin.tie(nullptr);
	//cout.tie(nullptr);
	ll n;
	cin >> n;
	for(ll i = 0; i < n; i++){
		cin >> a[i] >> b[i];
		ax[i] = a[i];
		bx[i] = b[i];
	}
	sort(ax, ax + n);
	sort(bx, bx + n);
	ll sza = unique(ax, ax + n) - ax;
	ll szb = unique(bx, bx + n) - bx;
	for(ll i = 0; i < n; i++){
		a[i] = lower_bound(ax, ax + sza, a[i]) - ax;
		b[i] = lower_bound(bx, bx + szb, b[i]) - bx;
		cnt[b[i]]++;
		in[a[i]].pb(b[i]);
	}
	ll ans = 0;
	for(ll i = 0; i < sza; i++){
		ll k1 = (ll)in[i].size(), sum =0;
		for(auto u : in[i]){
			sum += cnt[u];
		}
		sum -= k1;
		//cout << i << " "<< k1 << " " << sum << endl;
		for(auto u : in[i]){
			k1--;
			ans += sum * k1;
			sum = sum - cnt[u] + 1;
		}
	}
	cout << ans;
  return 0;
}

• Subtask 1: 0 / 100