Submission #595156

#	Time	Username	Problem	Language	Result	Execution time	Memory
595156		alexdd	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	469 ms	22416 KiB

commuter_pass

#include<iostream>
#include<vector>
#include<queue>
#include<tuple>
#include<algorithm>
#include<climits>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<long long, long long>
#define INF LLONG_MAX/2
ll n,m,s,t,u,v,ans;
vector<pii> con[100005];
ll du[100005];
ll dv[100005];
void dijkstra(ll src, ll dist[])
{
    for(int i=0;i<=n;i++)
        dist[i]=INF;
    dist[src]=0;
    priority_queue<pii, vector<pii>, greater<pii>> pq;
    pq.push({0,src});
    ll cdist,nod,adj,w;
    while(!pq.empty())
    {
        tie(cdist,nod)=pq.top();
        pq.pop();
        if(cdist!=dist[nod])
            continue;
        for(auto aux:con[nod])
        {
            tie(adj,w)=aux;
            if(dist[adj]>dist[nod]+w)
            {
                dist[adj]=dist[nod]+w;
                pq.push({dist[adj],adj});
            }
        }
    }
}
ll dpu[100005];
ll dpv[100005];
ll dst[100005];
void dijkstra_parent(ll src, ll ult)
{
    for(int i=0;i<=n;i++)
        dpu[i]=dpv[i]=dst[i]=INF;
    priority_queue<pii,vector<pii>,greater<pii>> pq;
    pq.push({0,src});
    dst[src]=0;
    dpu[src]=du[src];
    dpv[src]=dv[src];
    ll cdist,nod,adj,w;
    while(!pq.empty())
    {
        tie(cdist,nod)=pq.top();
        pq.pop();
        if(cdist!=dst[nod])
            continue;
        for(auto aux:con[nod])
        {
            tie(adj,w)=aux;
            if(dst[adj]>dst[nod]+w)
            {
                dst[adj]=dst[nod]+w;
                dpu[adj]=min(du[adj], dpu[nod]);
                dpv[adj]=min(dv[adj], dpv[nod]);
                pq.push({dst[adj],adj});
            }
            else if(dst[adj]==dst[nod]+w && min(du[adj], dpu[nod])+min(dv[adj], dpv[nod])<dpu[adj]+dpv[adj])
            {
                dpu[adj]=min(du[adj], dpu[nod]);
                dpv[adj]=min(dv[adj], dpv[nod]);
            }
        }
    }
    ans=min(ans,dpu[ult]+dpv[ult]);
}
int main()
{
    ll a,b,c;
    cin>>n>>m>>s>>t>>u>>v;
    for(ll i=1;i<=m;i++)
    {
        cin>>a>>b>>c;
        con[a].pb({b,c});
        con[b].pb({a,c});
    }
    dijkstra(u,du);
    dijkstra(v,dv);
    ans=du[v];
    dijkstra_parent(s,t);
    dijkstra_parent(t,s);
    cout<<ans<<"\n";
}

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