Submission #896052

#	Time	Username	Problem	Language	Result	Execution time	Memory
896052		thunopro	Star triangles (IZhO11_triangle)	C++14	100 / 100	618 ms	42844 KiB

triangle

#include<bits/stdc++.h>
using namespace std ; 
#define ll long long 
#define maxn 200009 
#define fi first 
#define se second 
#define pb push_back 
#define left id<<1 
#define right id<<1|1 
#define re exit(0); 
#define _lower(x) lower_bound(v.begin(),v.end(),x)-v.begin()+1  

const int mod = 1e9+7 ; 
const int INF = 1e9 ; 
const int LOG = 18 ; 

typedef vector<int> vi ; 
typedef pair<int,int> pii ; 
typedef vector<ll> vl ; 
typedef vector<pii> vii ; 
 
void add ( int &a , int b ) 
{
	a += b ;
	if ( a < 0 ) a += mod ; 
	if ( a >= mod ) a -= mod ; 
}

template < typename T > void chkmin ( T &a , T b ) { if ( a > b ) a = b ; } 
template < typename T > void chkmax ( T &a , T b ) { if ( a < b ) a = b ; } 

void rf () 
{
	freopen ("bai1.inp","r",stdin) ; 
//	freopen ("bai1.out","w",stdout) ; 
}

int _pow ( int a , int n ) 
{
	if ( n == 0 ) return 1 ; 
	int res = _pow (a,n/2) ; 
	if ( n % 2 ) return 1ll*res*res%mod*a%mod ; 
	else return 1ll*res*res%mod ; 
}

int n ; 
map <int,int> mp_x , mp_y ; 
map <ll,int> mp ; 

ll get_hash ( int x , int y ) 
{
	return 1ll*x*INF+y+1ll*mod*mod ; 
}
int main () 
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);cout.tie(0) ; 
//	rf () ; 
	cin >> n ; 
	set <pii> S ; 
	for ( int i = 1 ; i <= n ; i ++ ) 
	{
		int x , y ; cin >> x >> y ; 
		mp_x [x] ++ , mp_y [y] ++ ; 
		S.insert ({x,y}) ; 
		mp [get_hash(x,y)] ++ ; 
	}
	
	ll res = 0 ; 
	for ( auto x : S ) 
	{
		res += 1ll*(mp_x[x.fi]-mp[get_hash(x.fi,x.se)])*(mp_y[x.se]-mp[get_hash(x.fi,x.se)]) ; 
	}
	cout << res ; 
}

// range , error , check special , ... 
// find key , find key 
//'-std=c++11' stay hard 
// there is no tomorrow 

Compilation message (stderr)

triangle.cpp: In function 'void rf()':
triangle.cpp:34:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |  freopen ("bai1.inp","r",stdin) ;
      |  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100