Submission #1265338

#	Time	Username	Problem	Language	Result	Execution time	Memory
1265338		marcus06	Commuter Pass (JOI18_commuter_pass)	C++20	31 / 100	321 ms	19660 KiB

commuter_pass

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

#ifdef LOCAL
#include </home/marcus06/CP/Library/debug.h>
#else
#define debug(...) 
#endif

const int N = int(1e5) + 5;
const lli INF = lli(1e18) + 7;

int n, m;
int S, T, U, V;
vector <pair <int, int>> graph[N];
lli from_S[N], from_T[N], from_U[N], from_V[N];
lli f[N], g[N];

void Dijkstra(int src, lli dist[]) {
    for (int i = 0; i < n; ++i) dist[i] = -1;
    priority_queue <pair <lli, int>> Q;

    dist[src] = 0;
    Q.emplace(0, src);
    while (!Q.empty()) {
        auto [d, u] = Q.top(); Q.pop();
        d = -d;
        if (d != dist[u]) continue;
        
        for (auto [v, w]: graph[u]) {
            if (dist[v] == -1 || dist[v] > dist[u] + w) {
                dist[v] = dist[u] + w;
                Q.emplace(-dist[v], v);
            }
        }
    }
}

bool onShortest(int u, int v, int w) {
    return (from_S[u] + from_T[v] + w == from_S[T]);
}

bool visited[N];
void dfs(int u) {
    f[u] = from_U[u];
    g[u] = from_V[u];
    visited[u] = true;
    for (auto [v, w]: graph[u]) {
        if (visited[v] || !onShortest(u, v, w)) continue;
        dfs(v);
        f[u] = min(f[u], f[v]);
        g[u] = min(g[u], g[v]);
    }
}

void solve() {
    cin >> n >> m;
    cin >> S >> T >> U >> V;
    --S, --T, --U, --V;
    for (int i = 0; i < m; ++i) {
        int u, v, w;
        cin >> u >> v >> w;
        --u, --v;
        graph[u].emplace_back(v, w);
        graph[v].emplace_back(u, w);
    }

    Dijkstra(S, from_S);
    Dijkstra(T, from_T);
    Dijkstra(U, from_U);
    Dijkstra(V, from_V);

    for (int i = 0; i < n; ++i) {
        f[i] = g[i] = INF;
    }
    dfs(S);

    lli ans = from_U[V];
    for (int i = 0; i < n; ++i) {
        ans = min(ans, from_U[i] + g[i]);
        ans = min(ans, from_V[i] + f[i]);
    }
    cout << ans << '\n';
}

int main() {
    std::cin.tie(0)->sync_with_stdio(0);
#ifdef LOCAL
    auto begin = std::chrono::high_resolution_clock::now();
#endif

    int tt = 1;
    while (tt--) {
        solve();
    }

#ifdef LOCAL
    auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
    std::cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
#endif
    return 0;
}

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