Submission #1015491

#	Time	Username	Problem	Language	Result	Execution time	Memory
1015491		Minbaev	Star triangles (IZhO11_triangle)	C++17	0 / 100	2 ms	348 KiB

triangle

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> 
 
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("Ofast,unroll-loops")
 
using namespace std;
using namespace __gnu_pbds;
 
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define f first
#define s second
#define int long long
#define pii pair<int,int>
 
template<class T>bool umax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<class T>bool umin(T &a,T b){if(b<a){a=b;return true;}return false;}
 
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
 tree_order_statistics_node_update> ordered_set;
 
const int inf = 1e17 + 7;
const int mod = 1e9 + 7;
const int md = 998244353;
const int N = 2e5 + 5;

int binpow(int a, int b){
	if(b == 0)return 1;
	if(b % 2 == 0){
		int c = binpow(a,b/2);
		return (c*c)%mod;
	}
	return (binpow(a,b-1)*a)%mod;
}

int divi(int a, int b){
	return (a*(binpow(b,mod-2)))%mod;
}

int n,m,k;

void solve(){
	
	cin >> n;
	vector<pii>v(n);
	for(auto &to:v)cin >> to.f >> to.s;
	
	map<int,int>x;
	map<int,int>y;
	
	for(auto to:v){
		x[to.f] += 1;
		y[to.s] += 1;
	}
	int ans = 0;
	for(auto to:v){
		x[to.f] -= 1;
		y[to.s] -= 1;
		ans += x[to.f] * y[to.s];
		x[to.f] += 1;
		y[to.s] += 1;
	}
	cout << ans << "\n";
	
}
 /*
 209715
 */
 signed main()
{
	freopen("triangles.in", "r", stdin);
	freopen("triangles.out", "w", stdout);
	ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
	int tt=1;//cin>>tt;
	while(tt--)solve();
 
}
 

Compilation message (stderr)

triangle.cpp: In function 'int main()':
triangle.cpp:73:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |  freopen("triangles.in", "r", stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
triangle.cpp:74:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |  freopen("triangles.out", "w", stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 100