Submission #1350626

#TimeUsernameProblemLanguageResultExecution timeMemory
1350626guardianecCommuter Pass (JOI18_commuter_pass)C++20
15 / 100
400 ms327680 KiB
#include <bits/stdc++.h>
#define ll long long
using namespace std;

void findp(ll curr, vector<ll> parent[], vector<ll>& path, vector<vector<ll>>& p) {
    if (curr==-1) {
        vector<ll> p1 = path;
        reverse(p1.begin(), p1.end());
        p.push_back(p1);
        return;
    }

    for (auto pp : parent[curr]) {
        path.push_back(curr);
        findp(pp, parent, path, p);
        path.pop_back();
    }
}

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

    ll n,m;
    cin >> n >> m;
    ll s,t,u1,v1;
    cin >> s >> t >> u1 >> v1;
    s--; t--; u1--; v1--;
    vector<vector<pair<ll,ll>>> adj(n);
    for (int i=0; i<m; i++) {
        ll u,v,c;
        cin >> u >> v >> c;
        u--; v--;
        adj[u].push_back({v,c});
        adj[v].push_back({u,c});
    }

    priority_queue<pair<ll,ll>, vector<pair<ll,ll>>, greater<pair<ll,ll>>> pq;
    pq.push({0, s});
    vector<ll> dist(n, 1e18);
    dist[s] = 0;
    vector<ll> parent[n];
    parent[s].push_back(-1);
    while(!pq.empty()) {
        auto [d,u] = pq.top();
        pq.pop();
        if (d>dist[u]) continue;

        for (auto [v,w] : adj[u]) {
            if (dist[u]+w<dist[v]) {
                dist[v] = dist[u]+w;
                pq.push({dist[v], v});
                parent[v].clear();
                parent[v].push_back(u);
            } else if (dist[u]+w==dist[v]) {
                parent[v].push_back(u);
            }
        }
    }

    vector<vector<ll>> p;
    vector<ll> path;
    findp(t, parent, path, p);
    
    ll res = 1e18;
    for (auto p1 : p) {
        vector<vector<pair<ll,ll>>> adj1 = adj;
        for (int i=1; i<p1.size(); i++) {
            adj1[p1[i]].push_back({p1[i-1], 0});
            adj1[p1[i-1]].push_back({p1[i], 0});
        }

        for (int i=0; i<n; i++) dist[i] = 1e18;
        dist[u1] = 0;
        pq.push({0, u1});
        while(!pq.empty()) {
            auto [d,u] = pq.top();
            pq.pop();
            if (d>dist[u]) continue;

            for (auto [v,w] : adj1[u]) {
                if (dist[v]>dist[u]+w) {
                    dist[v] = dist[u]+w;
                    pq.push({dist[v], v});
                }
            }
        }

        res = min(res, dist[v1]);
    }

    cout << res;
}
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