Submission #679374

#	Time	Username	Problem	Language	Result	Execution time	Memory
679374		kusssso	Commuter Pass (JOI18_commuter_pass)	C++17	55 / 100	504 ms	27252 KiB

commuter_pass

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e5 + 5;
const ll inf = 1e18;
typedef pair<int, ll> edge;
#define fi first
#define se second

struct Node {
    ll fu;
    int u;
    bool hu, hv;
    bool operator < (const Node& oth) const {
        return fu > oth.fu;
    }  
};

int n, m;
int S, T, U, V;
ll f[N][2][2];
vector<edge> g[N];

vector<ll> Dij (int st) {
    vector<ll> d(n + 1, inf);
    d[st] = 0;
    priority_queue<pair<ll, int>> pq;
    pq.push({0, st});
    while (!pq.empty()) {
        ll du = -pq.top().fi;
        int u = pq.top().se;
        pq.pop();
        if (d[u] != du) continue;
        for (auto e : g[u]) {
            int v = e.fi;
            ll w = e.se;
            if (d[v] > d[u] + w) {
                d[v] = d[u] + w;
                pq.push({-d[v], v});
            }
        }
    }
    return d;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> n >> m >> S >> T >> U >> V;
    for (int i = 0; i < m; i++) {
        int u, v, c;
        cin >> u >> v >> c;
        g[u].push_back({v, c});
        g[v].push_back({u, c});
    }
    vector<ll> ds = Dij(S);
    vector<ll> du = Dij(U);
    vector<ll> dv = Dij(V);
    
    ll ans = du[V];
    
    for (int i = 0; i <= n; i++) {
        for (int j = 0; j < 2; j++) {
            for (int x = 0; x < 2; x++) {
                f[i][j][x] = inf;
            }
        }
    }
    
    priority_queue<Node> pq;
    pq.push({0, S, (S == U), (S == V)});
    f[S][S == U][S == V] = 0;
    
    while (!pq.empty()) {
        auto [fu, u, hu, hv] = pq.top(); pq.pop();
        if (fu != f[u][hu][hv]) continue;
        // if (u == 5) {
            // cout << "yes\n";
        // }
        for (auto [v, c] : g[u]) {
            if (ds[v] == ds[u] + c) {
                bool nhu = hu | (v == U);
                bool nhv = hv | (v == V);
                if (f[v][nhu][nhv] > fu) {
                    f[v][nhu][nhv] = fu;
                    pq.push({f[v][nhu][nhv], v, nhu, nhv});
                }
                if (!nhu) {
                    if (f[v][1][nhv] > fu + du[v]) {
                        f[v][1][nhv] = fu + du[v];
                        pq.push({f[v][1][nhv], v, 1, nhv});
                    }
                }
                if (!nhv) {
                    if (f[v][nhu][1] > fu + dv[v]) {
                        f[v][nhu][1] = fu + dv[v];
                        pq.push({f[v][nhu][1], v, nhu, 1});
                    }
                }
                if (!nhu && !nhv) {
                    if (f[v][1][1] > fu + du[v] + dv[v]) {
                        f[v][1][1] = fu + du[v] + dv[v];
                        pq.push({f[v][1][1], v, 1, 1});
                    }
                }
            }
        }
    }
    ans = min(ans, f[T][1][1]);
    cout << ans;
    
    return 0;
}

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