Submission #714227

#	Time	Username	Problem	Language	Result	Execution time	Memory
714227		Luicosas	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	588 ms	27736 KiB

commuter_pass

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

#define pb push_back
#define sz(x) (int)(x.size())
#define itr(x) x.begin(), x.end()
#ifdef LOC
#define prv(x) cerr << #x << " : "; for(auto& ov : x) cout << ov << " "; cout << "\n";
#define debug(...) cerr << #__VA_ARGS__ << " : "; for(auto& dval : {__VA_ARGS__}) cerr << dval << " "; cerr << "\n";
#else
#define debug(...)
#define prv(x)
#define LOC 0
#endif

void dijkstra(int s, vector<vector<array<ll,2>>>& adj, vector<ll>& dis) {
    priority_queue<array<ll,2>> que;
    que.push({0, s});
    while(sz(que)) {
        ll idx = que.top()[1], d = -que.top()[0];
        que.pop();

        if(dis[idx] <= d) {
            continue;
        }
        dis[idx] = d;

        for(auto& e : adj[idx]) {
            que.push({-(d + e[1]), e[0]});
        }
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if(LOC) {
        cerr << "debug mode\n";
    }

    int n, m, s, t, u, v;
    cin >> n >> m >> s >> t >> u >> v;
    s--; t--; u--; v--;

    vector<array<ll,3>> edges(m);
    for(auto& e : edges) {
        cin >> e[0] >> e[1] >> e[2];
        e[0]--; e[1]--;
    }

    vector<vector<array<ll,2>>> G(n);
    for(auto& e : edges) {
        G[e[0]].pb({e[1], e[2]}); 
        G[e[1]].pb({e[0], e[2]}); 
    }

    vector<ll> sd(n, INT64_MAX), td(n, INT64_MAX), ud(n, INT64_MAX), vd(n, INT64_MAX);
    dijkstra(s, G, sd);
    dijkstra(t, G, td);
    dijkstra(u, G, ud);
    dijkstra(v, G, vd);

    vector<int> in(n, 0);
    vector<vector<int>> dag(n);
    for(auto& e : edges) {
        if(sd[e[0]] + e[2] + td[e[1]] == td[s]) {
            dag[e[0]].pb(e[1]);
            in[e[1]]++;
        }
        if(sd[e[1]] + e[2] + td[e[0]] == td[s]) {
            dag[e[1]].pb(e[0]);
            in[e[0]]++;
        }
    }
    prv(in);

    vector<int> que;
    vector<ll> mnud(n, INT64_MAX / 2), mnvd(n, INT64_MAX / 2);
    for(int i = 0; i < n; i++) {
        if(in[i] == 0) {
            que.pb(i);
        }
    }
    ll ans = ud[v];
    while(sz(que) > 0) {
        int idx = que.back();
        que.pop_back();

        mnud[idx] = min(mnud[idx], ud[idx]);
        mnvd[idx] = min(mnvd[idx], vd[idx]);

        ans = min(ans, mnud[idx] + vd[idx]);
        ans = min(ans, mnvd[idx] + ud[idx]);
        debug((ll)idx, ans);

        for(int e : dag[idx]) {
            mnud[e] = min(mnud[e], mnud[idx]);
            mnvd[e] = min(mnvd[e], mnvd[idx]);

            in[e]--;
            if(in[e] == 0) {
                que.pb(e);
            }
        }
    }
    prv(ud);
    prv(vd);
    prv(mnud);
    prv(mnvd);
    cout << ans << "\n";
}

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