Submission #852667

#	Time	Username	Problem	Language	Result	Execution time	Memory
852667		nghiaaa	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	266 ms	29772 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define db double
#define ii pair<int,int>
#define f first
#define s second
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define ALL(v) v.begin(),v.end()
#define BIT(i) ((ll)1<<i)
#define endl "\n"
#define debug(x) for (auto p: x) cout<<p<<' ';cout<<endl
#define forw(i,j,z) for(int i=(int)j;i<=(int)z;i++)
#define forw2(i,j,z,k) for(int i=(int)j;i<=(int)z;i+=k)
#define ford(i,j,z) for (int i=(int)j;i>=(int)z;i--)
#define ford2(i,j,z,k) for (int i=(int)j;i>=(int)z;i-=k)
#define sz(a) (int)a.size()
const ll inf=BIT(60);
const int N=100000;
int n,m,s;
struct Edge{
    int nex;ll cost;
    Edge(int v1,ll d1)
    {
        nex=v1,cost=d1;
    }
};
vector<Edge> a[N+1];
vector<ll> S,U,V,dpU,dpV;
vector<vector<int> > traceS;
ll ans;
bitset<N+1> vis;
void dijkstra(int S,vector<ll> &dp,bool TRACE)
{
    dp.assign(n+1,LLONG_MAX);
    dp[S]=0;
    priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > haha;
    haha.push(mp(0LL,S));
    while(!haha.empty())
    {
        pair<ll,int> temp = haha.top();
        haha.pop();
        int u=temp.s;
        if (temp.f>dp[u]) continue;
        forw(i,0,sz(a[u])-1)
        {
            int v=a[u][i].nex,d=a[u][i].cost;
            if (dp[u]+d<dp[v])
            {
                if (TRACE)
                {
                    traceS[v].clear();
                    traceS[v].pb(u);
                }
                dp[v]=dp[u]+d;
                haha.push(mp(dp[v],v));
            }
            else if (TRACE&&dp[u]+d==dp[v])
                traceS[v].pb(u);
        }
    }
}
void dfs(int u)
{
    vis[u]=1;
    if (u==s)
    {
        dpU[u]=U[s],dpV[u]=V[s];
        ans=min(ans,dpU[u]+dpV[u]);
        return ;
    }
    dpU[u]=U[u],dpV[u]=V[u];
    forw(i,0,sz(traceS[u])-1)
    {
        int v=traceS[u][i];
        if (!vis[v]) dfs(v);
        dpU[u]=min(dpU[u],dpU[v]);
        dpV[u]=min(dpV[u],dpV[v]);
    }
    ans=min(ans,min(dpU[u]+V[u],dpV[u]+U[u]));
}
void solve()
{
    int u,v,t;
    cin>>n>>m;
    cin>>s>>t>>u>>v;
    traceS.assign(n+1,vector<int>(0,0));
    dpU.assign(n+1,0);
    dpV.assign(n+1,0);
    while(m--)
    {
        int u,v;ll d;
        cin>>u>>v>>d;
        a[u].pb(Edge(v,d));
        a[v].pb(Edge(u,d));
    }
    dijkstra(s,S,1);
    dijkstra(u,U,0);
    dijkstra(v,V,0);
    ans=U[v];
    dfs(t);
    cout<<ans;
}
signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout<<setprecision(6)<<fixed;
    int t=1;
    while(t--)
        solve();
    return 0;
}

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