Submission #1182901

#	Time	Username	Problem	Language	Result	Execution time	Memory
1182901		Warinchai	Commuter Pass (JOI18_commuter_pass)	C++20	15 / 100	333 ms	54072 KiB

commuter_pass

#include<bits/stdc++.h>
#define int long long
using namespace std;
vector<pair<int,int>>adj[200005];
int dis[200005];
int inf=1e15;
vector<int>back[200005];
int vis[200005];
int n,m;
vector<pair<int,int>>edge;
void dijkstra(int s){
    priority_queue<pair<int,pair<int,int>>,vector<pair<int,pair<int,int>>>,greater<pair<int,pair<int,int>>>>pq;
    for(int i=1;i<=n;i++)dis[i]=inf;
    pq.push({0,{s,s}});
    while(!pq.empty()){
        auto [d,x]=pq.top();
        int u=x.first;
        int p=x.second;
        pq.pop();
        if(d<=dis[u])back[u].push_back(p);
        if(d>=dis[u])continue;
        dis[u]=d;
        for(auto x:adj[u]){
            pq.push({x.second+d,{x.first,u}});
        }
    }
}
void bt(int u,int s){
    if(u==s)return;
    for(auto x:back[u]){
        if(!vis[x])edge.push_back({x,u}),bt(x,u),vis[x]=1;
    }
}
int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m;
    int s,t;cin>>s>>t;
    int u,v;cin>>u>>v;
    for(int i=0;i<m;i++){
        int a,b,c;cin>>a>>b>>c;
        adj[a].push_back({b,c});
        adj[b].push_back({a,c});
    }
    dijkstra(s);
    //for(int i=1;i<=n;i++)cerr<<dis[i]<<" ";
    //cerr<<"\n";
    vis[t]=1;
    bt(t,s);
    for(auto x:edge){
        adj[x.first].push_back({x.second,0});
    }
    int ans=inf;
    dijkstra(u);
    //for(int i=1;i<=n;i++)cerr<<dis[i]<<" ";
    //cerr<<"\n";
    ans=min(ans,dis[v]);
    dijkstra(v);
    ans=min(ans,dis[u]);
    cout<<ans;
}

• Subtask 1: 0 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45