Submission #620081

#	Time	Username	Problem	Language	Result	Execution time	Memory
620081		chonka	Port Facility (JOI17_port_facility)	C++17	100 / 100	961 ms	85412 KiB

port_facility

#include<bits/stdc++.h>
using namespace std ;
typedef long long ll ;
typedef unsigned long long ull ;
#define fi first
#define se second
// mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

const int MAXN = 2e6 + 7 ;
const int MOD = 1e9 + 7 ;

int n ;
pair < int , int > a[ MAXN ] ;
int prv[ MAXN ] , rnk[ MAXN ] ;

int get ( int x ) {
    if ( prv[ x ] == -1 ) { return x ; }
    int y = get ( prv[ x ] ) ;
    prv[ x ] = y ;
    return y ;
}

void unite ( int x , int y ) {
    int k1 = get ( x ) , k2 = get ( y ) ;
    if ( k1 != k2 ) {
        if ( rnk[ k1 ] >= rnk[ k2 ] ) {
            rnk[ k1 ] += ( rnk[ k1 ] == rnk[ k2 ] ) ;
            prv[ k2 ] = k1 ;
        }
        else {
            prv[ k1 ] = k2 ;
        }
    }
}

void solve ( ) {
    cin >> n ;
    for ( int i = 1 ; i <= n ; ++ i ) {
        cin >> a[ i ].fi >> a[ i ].se ;
    }
    sort ( a + 1 , a + n + 1 ) ;
    for ( int i = 1 ; i <= 2 * n ; ++ i ) {
        prv[ i ] = -1 , rnk[ i ] = 0 ;
    }
    set < pair < int , int > > s ;
    for ( int i = 1 ; i <= n ; ++ i ) {
        auto it = s.lower_bound ( { a[ i ].fi , 0 } ) ;
        auto en = s.lower_bound ( { a[ i ].se , 0 } ) ;
        auto aux = en ; -- aux ;
        while ( it != en ) {
            unite ( i , it->se + n ) ;
            unite ( i + n , it->se ) ;

            if ( get ( it->se ) == get ( aux->se ) ) { break ; }
            ++ it ;
        }
        if ( get ( i ) == get ( n + i ) ) {
            cout << "0\n" ;
            return ;
        }
        s.insert ( { a[ i ].se , i } ) ;
    }
    ll ans = 1 ;
    for ( int i = 1 ; i <= n ; ++ i ) {
        if ( get ( i ) == i ) {
            ans = ( ans * 2 ) % MOD ;
        }
    }
    cout << ans << "\n" ;
}

int main ( ) {
    ios_base :: sync_with_stdio ( false ) ;
    cin.tie ( NULL ) ;
    int t = 1 ; // cin >> t ; 
    while ( t -- ) { solve ( ) ; }
    return 0 ;
}

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 56 / 56
• Subtask 4: 22 / 22