제출 #1222283

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1222283		ffeyyaae_	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	159 ms	19912 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const int N = 1e5+5;
const ll INF = LLONG_MAX/2;

int n, m, u, v, s, t;
vector<pair<int,int>> adj[N];
vector<int> adj2[N];
ll disu[N], disv[N], disS[N];
ll dp[N][2][2];

void dijkstra( int st, ll dis[] )
{
    for( int i=1;i<=n;i++ ) dis[i] = INF;
    dis[st] = 0;
    priority_queue<pair<ll,ll>, vector<pair<ll,ll>>, greater<pair<ll,ll>>> pq;
    pq.push( {0, st} );
    while( !pq.empty() )
    {
        auto [cost, u] = pq.top();
        pq.pop();
        for( auto [v, w] : adj[u] )
        {
            if( dis[v] > cost+w )
            {
                dis[v] = cost+w;
                pq.push( {cost+w, v} );
            }
        }
    }
}

int main()  
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n >> m >> s >> t >> u >> v;
    while( m-- )
    {
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].push_back( {v, w} );
        adj[v].push_back( {u, w} );
    }
    dijkstra( u, disu );
    dijkstra( v, disv );
    dijkstra( s, disS );
    for( int u=1;u<=n;u++ )
    {
        for( auto [v, w] : adj[u] )
        {
            if( disS[v]+w == disS[u] )
            {
                adj2[u].push_back( v );
            }
        }
    }
    vector<int> ord(n);
    iota( ord.begin(), ord.end(), 1 );
    sort( ord.begin(), ord.end(), [&](int i, int j){
        return disS[i] < disS[j];
    } );
    for( int i=1;i<=n;i++ )
    {
        for( int j=0;j<2;j++ ) for( int k=0;k<2;k++ ) dp[i][j][k] = INF;
    }
    dp[s][0][0] = 0;
    for( auto u : ord )
    {
        for( auto v : adj2[u] )
        {
            for( int i=0;i<2;i++ )
            {
                for( int j=0;j<2;j++ ) dp[u][i][j] = min( dp[u][i][j], dp[v][i][j] );
            }
        }
        dp[u][0][1] = min( dp[u][0][1], dp[u][0][0]+disu[u] );
        dp[u][1][0] = min( dp[u][1][0], dp[u][0][0]+disv[u] );
        dp[u][1][1] = min( {dp[u][1][1], dp[u][1][0]+disu[u], dp[u][0][1]+disv[u]} );
    }
    cout << min( dp[t][1][1], disu[v] ) << "\n";
}

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45