Submission #931740

#	Time	Username	Problem	Language	Result	Execution time	Memory
931740		sofijavelkovska	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	267 ms	25240 KiB

commuter_pass

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

const int MAXN=100001;
const long long INF=1e16;

int n, m, s, t, u, v;
vector<pair<int, int> > adj[MAXN];
vector<int> shortadj[MAXN];
long long mincost=INF;
long long mindist[MAXN];

void dijkstra(int root, long long dist[])
{
    for (int i=1; i<=n; i++)
        dist[i]=INF;
    dist[root]=0;
    bool visited[n+1]={false};
    priority_queue<pair<long long, int> > pq;
    pq.push({0, root});
    while (!pq.empty())
    {
        int x=pq.top().second;
        pq.pop();
        if (visited[x])
            continue;
        visited[x]=true;
        for (auto edge : adj[x])
        {
            int y=edge.first;
            int w=edge.second;
            if (dist[x]+w<dist[y])
            {
                dist[y]=dist[x]+w;
                pq.push({-dist[y], y});
            }
        }
    }

    return;
}

long long findmin(int x, long long dist1[], long long dist2[])
{
    if (mindist[x]!=-1)
        return mindist[x];
    mindist[x]=dist1[x];
    for (auto y : shortadj[x])
        mindist[x]=min(mindist[x], findmin(y, dist1, dist2));
    mincost=min(mincost, mindist[x]+dist2[x]);

    return mindist[x];
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;
    cin >> s >> t >> u >>  v;
    long long sdist[n+1], tdist[n+1], udist[n+1], vdist[n+1];
    for (int i=0; i<m; i++)
    {
        int x, y, w;
        cin >> x >> y >> w;
        adj[x].push_back({y, w});
        adj[y].push_back({x, w});
    }
    dijkstra(s, sdist);
    dijkstra(t, tdist);
    dijkstra(u, udist);
    dijkstra(v, vdist);
    queue<int> q;
    q.push(s);
    bool visited[n+1]={false};
    while (!q.empty())
    {
        int x=q.front();
        q.pop();
        if (visited[x])
            continue;
        visited[x]=true;
        for (auto edge : adj[x])
        {
            int y=edge.first;
            int w=edge.second;
            if (sdist[x]+w>sdist[y])
                continue;
            if (sdist[y]+tdist[y]!=sdist[t])
                continue;
            shortadj[x].push_back(y);
            q.push(y);
        }
    }
    for (int i=1; i<=n; i++)
        mindist[i]=-1;
    findmin(s, udist, vdist);
    for (int i=1; i<=n; i++)
        mindist[i]=-1;
    findmin(s, vdist, udist);
    mincost=min(mincost, udist[v]);
    cout << mincost;

    return 0;
}

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