Submission #884795

#	Time	Username	Problem	Language	Result	Execution time	Memory
884795		tosivanmak	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	261 ms	35016 KiB

commuter_pass

#include<bits/stdc++.h>
using namespace std;
#define ll long long

vector<pair<ll,ll> >adj[200005];
ll dist[200005];
ll fromu[200005],fromv[200005],cop[200005];
bool visited[200005];
priority_queue<pair<ll,ll> >q;
ll ans[200005],ans2[200005];
ll stdist,uvdist;
void D(ll s){
    dist[s]=0;
    q.push({0,s});
    while(!q.empty()){
        pair<ll,ll>lol=q.top();
        q.pop();
        if(visited[lol.second]){
            continue;
        }
        visited[lol.second]=true;
        for(auto u: adj[lol.second]){
            if(dist[lol.second]+u.second<dist[u.first]){
                dist[u.first]=dist[lol.second]+u.second;
                q.push({-dist[u.first],u.first});
            }
        }
    }
}
void D2(ll s){
    dist[s]=0;
    q.push({0,s});
    while(!q.empty()){
        pair<ll,ll>lol=q.top();
        q.pop();
        if(visited[lol.second]){
            continue;
        }
        visited[lol.second]=true;
        ans[lol.second]=min(ans[lol.second],fromu[lol.second]);
        for(auto u: adj[lol.second]){
            if(dist[lol.second]+u.second==dist[u.first]){
                ans[u.first]=min(ans[u.first],ans[lol.second]);
            }
            else if(dist[lol.second]+u.second<dist[u.first]){
                dist[u.first]=dist[lol.second]+u.second;
                ans[u.first]=ans[lol.second];
                q.push({-dist[u.first],u.first});
            }
        }
    }
}
void D3(ll s){
    dist[s]=0;
    q.push({0,s});
    while(!q.empty()){
        pair<ll,ll>lol=q.top();
        q.pop();
        if(visited[lol.second]){
            continue;
        }
        visited[lol.second]=true;
        ans2[lol.second]=min(ans2[lol.second],fromu[lol.second]);
        for(auto u: adj[lol.second]){
            if(dist[lol.second]+u.second==dist[u.first]){
                ans2[u.first]=min(ans2[u.first],ans2[lol.second]);
            }
            else if(dist[lol.second]+u.second<dist[u.first]){
                dist[u.first]=dist[lol.second]+u.second;
                ans2[u.first]=ans2[lol.second];
                q.push({-dist[u.first],u.first});
            }
        }
    }
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    ll n,m,s,t,u,v;
    cin>>n>>m>>s>>t>>u>>v;
    ll a[m+5],b[m+5],c[m+5];
    for(int i=1;i<=m;i++){
        cin>>a[i]>>b[i]>>c[i];
      adj[a[i]].push_back({b[i],c[i]});
      adj[b[i]].push_back({a[i],c[i]});
    }
    for(int i=1;i<=n;i++){
        dist[i]=1e17;
        visited[i]=false;
    }
    D(u);
    uvdist=dist[v];
    for(int i=1;i<=n;i++){
        fromu[i]=dist[i];
        // cout<<dist[i]<<" ";
        dist[i]=1e17;
        visited[i]=false;
    }
    // cout<<'\n';
    D(v);
    for(int i=1;i<=n;i++){
        fromv[i]=dist[i];
        // cout<<dist[i]<<" ";
        dist[i]=1e17;
        visited[i]=false;
    }
    for(int i=1;i<=n;i++){
       ans[i]=1e17;
       ans2[i]=1e17;
    //    cout<<ans[i]<<" ";
    }
    D2(s);
    stdist=dist[t];
    for(int i=1;i<=n;i++){
        cop[i]=dist[i];
        dist[i]=1e17;
        visited[i]=false;
    }
    D3(t);
    // cout<<uvdist<<'\n';
    for(int i=1;i<=n;i++){
        if(cop[i]+dist[i]==stdist){
            // cout<<i<<" "<<cop[i]<<" "<<dist[i]<<" ";
            // cout<<ans[i]<<" "<<fromv[i]<<'\n';
            uvdist=min(uvdist,min(ans[i],ans2[i])+fromv[i]);
            // cout<<i<<" ";
        }
    }
    // for(int i=1;i<=n;i++){
    //     cout<<ans[i]<<" "<<ans2[i]<<"\n";
    // }
    cout<<uvdist<<'\n';
}

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