Submission #538411

#	Time	Username	Problem	Language	Result	Execution time	Memory
538411		MohamedFaresNebili	Commuter Pass (JOI18_commuter_pass)	C++14	31 / 100	364 ms	22428 KiB

commuter_pass

#include <bits/stdc++.h>
/// #pragma GCC optimize ("Ofast")
/// #pragma GCC target ("avx2")

        using namespace std;

        using ll = long long;
        using ii = pair<ll, ll>;
        using vi = vector<int>;
        using db = double;

        #define ff first
        #define ss second
        #define pb push_back
        #define all(x) x.begin(), x.end()
        #define lb lower_bound
        #define ub upper_bound

        const ll INF = LONG_LONG_MAX;

        int n, m, s, t, from, to;
        vector<array<ll, 2>> adj[100005];
        ll dist[100005][2], best;
        void dijkstra(int src, int c) {
            for(int l = 0; l < n; l++)
                dist[l][c] = INF;
            priority_queue<ii, vector<ii>, greater<ii>> pq;
            pq.push({0, src}); dist[src][c] = 0; vector<bool> vis(n, 0);
            while(!pq.empty()) {
                int a = pq.top().ss; ll w = pq.top().ff; pq.pop();
                if(dist[a][c] < w || vis[a]) continue;
                vis[a] = 1;
                for(auto u : adj[a]) {
                    ll len = w + u[1];
                    if(vis[u[0]] || dist[u[0]][c] < len) continue;
                    dist[u[0]][c] = len;
                    pq.push({len, u[0]});
                }
            }
        }

        int32_t main() {
            ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
            cin >> n >> m >> s >> t >> from >> to;
            for(int l = 0; l < m; l++) {
                int u, v; ll w; cin >> u >> v >> w; u--; v--;
                adj[u].pb({v, w}); adj[v].pb({u, w});
            }
            s--; t--; from--; to--;
            dijkstra(s, 0); dijkstra(t, 1); best = dist[t][0];
            priority_queue<ii, vector<ii>, greater<ii>> pq;
            vector<ll> dis(n, INF); pq.push({0, from}); dis[from] = 0;

            while(!pq.empty()) {
                int a = pq.top().ss; ll w = pq.top().ff; pq.pop();
                if(dis[a] < w) continue;
                for(auto u : adj[a]) {
                    ll len = u[1] + w; bool ok = 0;

                    if(dist[a][0] + u[1] + dist[u[0]][1] == best) ok = 1;
                    if(dist[a][1] + u[1] + dist[u[0]][0] == best) ok = 1;

                    if(ok) len = w;

                    if(dis[u[0]] <= len) continue;
                    dis[u[0]] = len; pq.push({len, u[0]});
                }
            }
            cout << dis[to] << "\n";
        }

/**
8 8
5 7
6 8
1 2 2
2 3 3
3 4 4
1 4 1
1 5 5
2 6 6
3 7 7
4 8 8
**/

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