Submission #1173723

#	Time	Username	Problem	Language	Result	Execution time	Memory
1173723		mareksb	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	204 ms	21080 KiB

commuter_pass

#include <bits/stdc++.h>
#pragma GCC optimize ("O3,unroll-loops")
#pragma GCC target ("avx2,bmi,bmi2,popcnt,lzcnt")
using namespace std;
const int64_t N=100005;
vector<pair<int64_t,int64_t>> mas[N];
int64_t dS[N];
int64_t dT[N];
int64_t dV[N];
int64_t dU[N];
int64_t n,m;
int64_t s,t;//commuter pass
int64_t u,v;
void dijkstra(int64_t start, int64_t* dist){
    priority_queue<pair<int64_t,int64_t>,vector<pair<int64_t,int64_t>>,greater<pair<int64_t,int64_t>>> pq;
    dist[start]=0;
    pq.push({0,start});
    while(!pq.empty()){
        int64_t x=pq.top().second;
        pq.pop();

        for(auto p:mas[x]){
            if(dist[x]+p.second<dist[p.first]){
                dist[p.first]=dist[x]+p.second;
                pq.push({dist[p.first],p.first});
            }
        }
    }
}

bool vis[N];
bool vis2[N];
int64_t dpX[N];//best distance from x to v
int64_t dpY[N];//best distance from x to v
void dfs(int v, int dep=0){
    vis[v]=1;
    int64_t best=LLONG_MAX;
    //cout<<"lookup:"<<v<<' '<<dep<<'\n';
    for(auto p:mas[v]){
        int u=p.first;
        int c=p.second;
        if(dS[u]+dT[u]!=dS[t])continue;
        if(dT[u]>dT[v])continue;
        if(!vis[u]){
            dfs(u,dep+1);
        }
        
        best=min(best,dpX[u]);
    }

    dpX[v]=min(dV[v],best);
}
void dfs2(int v, int dep=0){
    vis2[v]=1;
    int64_t best=LLONG_MAX;
    //cout<<"lookup2:"<<v<<' '<<dep<<'\n';
    for(auto p:mas[v]){
        int u=p.first;
        int c=p.second;
        if(dS[u]+dT[u]!=dS[t])continue;
        if(dS[u]>dS[v])continue;
        if(!vis2[u]){
            dfs2(u,dep+1);
        }
        
        best=min(best,dpY[u]);
    }

    dpY[v]=min(dV[v],best);
}
void solve(){
    cin>>n>>m;
    for(int64_t i=0;i<=n;i++){
        dS[i]=LLONG_MAX/4;
        dT[i]=LLONG_MAX/4;
        dV[i]=LLONG_MAX/4;
        dU[i]=LLONG_MAX/4;
        dpX[i]=LLONG_MAX/4;
        dpY[i]=LLONG_MAX/4;
    }
    cin>>s>>t;
    cin>>u>>v;
    for(int64_t i=0;i<m;i++){
        int64_t x,y,c;
        cin>>x>>y>>c;
        mas[x].push_back({y,c});
        mas[y].push_back({x,c});
    }
    dijkstra(s,dS);
    dijkstra(t,dT);
    dijkstra(u,dU);
    dijkstra(v,dV);
    dfs(s);
    dfs2(t);
    int64_t ans=dU[v];
    //cout<<"0: "<<ans<<'\n';
    for(int x=1;x<=n;x++){
        ans=min({ans,dU[x]+dpX[x],dU[x]+dpY[x]});
        //cout<<x<<": "<<ans<<'\n';
    }
    cout<<ans<<'\n';
}

int main()
{
ios_base::sync_with_stdio(false);cin.tie(NULL);
    int64_t t=1;
    //cin>>t;
    while(t--){
        solve();
    }
    return 0;
}

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