Submission #1001422

#	Time	Username	Problem	Language	Result	Execution time	Memory
1001422		Icelast	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	407 ms	38280 KiB

commuter_pass

#include <iostream>
#include <bits/stdc++.h>
#define ll long long
#define int long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 4e18+9;
vector<ll> dijkstra(int s, vector<vector<pair<ll, ll>>> &adj){
    int n = adj.size();
    vector<ll> dist(n+1, INF);
    dist[s] = 0;
    vector<bool> vis(n+1, false);
    priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
    pq.push({0, s});
    while(!pq.empty()){
        ll d_u = pq.top().first;
        int u = pq.top().second;
        pq.pop();
        if(vis[u]){
            continue;
        }
        vis[u] = true;
        for(auto it : adj[u]){
            int v = it.first;
            ll w = it.second;
            if(vis[v]) continue;
            dist[v] = min(dist[v], d_u+w);
            pq.push({dist[v], v});
        }
    }
    return dist;
}
vector<ll> dijkstra2(vector<ll> dist, vector<vector<pair<ll, ll>>> &adj){
    int n = adj.size()-1;
    priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
    for(int i = 1; i <= n; i++) pq.push({dist[i], i});
    while(!pq.empty()){
        ll d_u = pq.top().first;
        int u = pq.top().second;
        pq.pop();
        if(d_u != dist[u]) continue;
        for(auto it : adj[u]){
            int v = it.first;
            ll w = it.second;
            if(dist[u]+w < dist[v]){
                dist[v] = dist[u]+w;
                pq.push({dist[v], v});
            }
        }
    }
    return dist;
}
void solve(){
    int n, m;
    cin >> n >> m;
    int S, T, U, V;
    cin >> S >> T;
    cin >> U >> V;
    vector<vector<pair<ll, ll>>> adj(n+1), adj1(n+1), adj2(n+1);
    for(int i = 1; i <= m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }
    vector<ll> ds = dijkstra(S, adj), dt = dijkstra(T, adj);
    for(int u = 1; u <= n; u++){
        if(ds[u]+dt[u] != ds[T]) continue;
        for(auto it : adj[u]){
            int v = it.first;
            ll w = it.second;
            if(ds[v]+dt[v] != ds[T]) continue;
            if(ds[u]+w == ds[v]){
                adj1[u].push_back({v, 0});
            }
            if(dt[u]+w == dt[v]){
                adj2[u].push_back({v, 0});
            }
        }
    }
    vector<ll> du1, du2;
    du1 = dijkstra(U, adj);
    du1 = dijkstra2(du1, adj1);
    du1 = dijkstra2(du1, adj);
    du2 = dijkstra(U, adj);
    du2 = dijkstra2(du2, adj2);
    du2 = dijkstra2(du2, adj);
    ll ans = INF;
    ans = min(du1[V], du2[V]);
    cout << ans << "\n";
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    //freopen("main.inp", "r", stdin);
    //freopen("main.out", "w", stdout);
    int t;
    t = 1;
    while(t--){
        solve();
    }
}

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