Submission #306421

#	Time	Username	Problem	Language	Result	Execution time	Memory
306421		vipghn2003	Commuter Pass (JOI18_commuter_pass)	C++14	0 / 100	2083 ms	262144 KiB

commuter_pass

#include<bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
using namespace std;

const int N=1e5+5;
int n,m,s,t,u,v,deg[N];
long long d[3][N],dp[N];
vector<int>g[N],topolist,rg[N];
vector<pii>adj[N];

void dijkstra(int i,int u)
{
    priority_queue<pair<long long,int>,vector<pair<long long,int>>,greater<pair<long long,int>>>pq;
    d[i][u]=0;
    pq.push(mp(0,u));
    while(!pq.empty())
    {
        int x=pq.top().se;
        long long dist=pq.top().fi;
        pq.pop();
        if(d[i][x]!=dist) continue;
        for(auto&to:adj[x])
        {
            if(d[i][to.fi]==-1||d[i][to.fi]>dist+to.se)
            {
                d[i][to.fi]=dist+to.se;
                pq.push(mp(d[i][to.fi],to.fi));
            }
        }
    }
}

void topo()
{
    queue<int>pq;
    pq.push(s);
    while(!pq.empty())
    {
        int x=pq.front();
        pq.pop();
        topolist.push_back(x);
        for(auto&to:g[x])
        {
            deg[to]--;
            if(deg[to]==0) pq.push(to);
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin>>n>>m>>s>>t>>u>>v;
    while(m--)
    {
        int u,v,w;
        cin>>u>>v>>w;
        adj[u].push_back(mp(v,w));
        adj[v].push_back(mp(u,w));
    }
    memset(d,-1,sizeof d);
    dijkstra(0,u);
    dijkstra(1,v);
    dijkstra(2,s);
    queue<int>cur;
    cur.push(t);
    while(!cur.empty())
    {
        int x=cur.front();
        cur.pop();
        for(auto&to:adj[x])
        {
            if(d[2][x]==d[2][to.fi]+to.se)
            {
                g[to.fi].push_back(x);
                rg[x].push_back(to.fi);
                deg[x]++;
                cur.push(to.fi);
            }
        }
    }
    topo();
    long long res=d[0][v];
    for(auto&x:topolist)
    {
        dp[x]=1e18;
        if(d[0][x]!=-1) dp[x]=d[0][x];
        for(auto&pre:rg[x]) dp[x]=min(dp[x],dp[pre]);
        if(d[1][x]!=-1) res=min(res,d[1][x]+dp[x]);
    }
    cout<<res;
}

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