Submission #1279731

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279731		hanguyendanghuy	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	568 ms	20308 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define fi first
#define se second
constexpr ll MAXN=1e5+5,MAXV=3e5,MOD=1e9+7,INF=1e18;
ll n,m,i,j,p,k,ans,dem,st,en,dist[3][MAXN],S,T,U,V,len[MAXN],miV[MAXN],miU[MAXN];
vector<pair<ll,ll>> adj[MAXN];
void dij(ll st,ll type){
    priority_queue<pair<ll,ll>> q;
    dist[type][st]=0;
    q.push({0,st});
    while(q.size()){
        auto k=q.top();q.pop();
        if(-k.fi>dist[type][k.se]) continue;
        for(auto x:adj[k.se]){
            if(dist[type][x.fi]>-k.fi+x.se){
                dist[type][x.fi]=-k.fi+x.se;
                q.push({-dist[type][x.fi],x.fi});
            }
        }
    }
}
void solve(int start, int end) {
    vector<ll> dist_from_start(n + 1, INF);
    vector<ll> min_du_on_path(n + 1, INF);
    vector<ll> min_dv_on_path(n + 1, INF);

    dist_from_start[start] = 0;
    min_du_on_path[start] = dist[1][start];
    min_dv_on_path[start] = dist[2][start];
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> pq;
    pq.push({0, start});

    while (!pq.empty()) {
        ll d = pq.top().first;
        int u = pq.top().second;
        pq.pop();

        if (d > dist_from_start[u]) {
            continue;
        }

        for (auto& edge : adj[u]) {
            int v_neighbor = edge.first;
            ll weight = edge.second;

            ll new_dist = dist_from_start[u] + weight;
            ll new_min_du = min(min_du_on_path[u], dist[1][v_neighbor]);
            ll new_min_dv = min(min_dv_on_path[u], dist[2][v_neighbor]);
            if (new_dist < dist_from_start[v_neighbor]) {
                dist_from_start[v_neighbor] = new_dist;
                min_du_on_path[v_neighbor] = new_min_du;
                min_dv_on_path[v_neighbor] = new_min_dv;
                pq.push({new_dist, v_neighbor});
            }
            else if (new_dist == dist_from_start[v_neighbor]) {
                if (new_min_du + new_min_dv < min_du_on_path[v_neighbor] + min_dv_on_path[v_neighbor]) {
                    min_du_on_path[v_neighbor] = new_min_du;
                    min_dv_on_path[v_neighbor] = new_min_dv;
                    pq.push({new_dist, v_neighbor});
                }
            }
        }
    }
    
    if (dist_from_start[end] != INF) {
        ans = min(ans, min_du_on_path[end] + min_dv_on_path[end]);
    }
}
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    cin>>n>>m>>S>>T>>U>>V;
    for(i=1;i<=m;i++){
        ll u,v,c;
        cin>>u>>v>>c;
        adj[u].pb({v,c});
        adj[v].pb({u,c});
    }
    for(i=1;i<=n;i++) dist[1][i]=dist[2][i]=INF;
    dij(U,1);
    dij(V,2);
    ans=dist[1][V];
    solve(S,T);
    solve(T,S);
    cout<<ans;
}

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