Submission #213060

#	Time	Username	Problem	Language	Result	Execution time	Memory
213060		DS007	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	617 ms	24308 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define int long long

const int N = 1e5;
int n, m, s, t, u, v;
vector<pair<int, int>> adj[N];
int du[N], dv[N], ds[N], dt[N];

void dijkstra(int src, int dist[]) {
    fill(dist, dist + N, 1e18);
    dist[src] = 0;

    priority_queue<pair<int, int>, vector<pair<int, int>>, decltype(greater<>())> pq;
    bool done[N] = {};
    pq.push({0, src});

    while (!pq.empty()) {
        int temp = pq.top().second;
        pq.pop();

        if (done[temp])
            continue;
        done[temp] = true;

        for (auto i : adj[temp]) {
            if (dist[i.first] > dist[temp] + i.second) {
                dist[i.first] = dist[temp] + i.second;
                pq.push({dist[i.first], i.first});
            }
        }
    }
}

int solve() {
    dijkstra(u, du);
    dijkstra(v, dv);
    dijkstra(t, dt);

    int mv[N];
    fill(mv, mv + N, 1e18);
    mv[s] = du[s];

    fill(ds, ds + N, 1e18);
    ds[s] = 0;

    priority_queue<pair<int, int>, vector<pair<int, int>>, decltype(greater<>())> pq;
    bool done[N] = {};
    pq.push({0, s});

    int ans = du[v];
    while (!pq.empty()) {
        int temp = pq.top().second;
        pq.pop();

        if (done[temp])
            continue;
        done[temp] = true;

        mv[temp] = min(mv[temp], du[temp]);
        if (ds[temp] + dt[temp] == dt[s])
            ans = min(ans, mv[temp] + dv[temp]);

        for (auto i : adj[temp]) {
            if (ds[i.first] > ds[temp] + i.second) {
                ds[i.first] = ds[temp] + i.second;
                pq.push({ds[i.first], i.first});
                mv[i.first] = mv[temp];
            } else if (ds[i.first] == ds[temp] + i.second) {
                mv[i.first] = min(mv[i.first], mv[temp]);
            }
        }
    }

    return ans;
}

void solveTestCase() {
    cin >> n >> m >> s >> t >> u >> v;
    s--, t--, u--, v--;

    for (int i = 0; i < m; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        a--, b--;
        adj[a].emplace_back(b, c);
        adj[b].emplace_back(a, c);
    }

    int ans = solve();
    swap(u, v);
    cout << min(ans, solve());
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int test = 1;
    // cin >> test;
    while (test--)
        solveTestCase();
}

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