Submission #1274712

#	Time	Username	Problem	Language	Result	Execution time	Memory
1274712		kduckp	Commuter Pass (JOI18_commuter_pass)	C++20	15 / 100	598 ms	49620 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e18;
const int N = 1e5 + 5;
vector<pair<int, ll>> adj[N];
int n, m, a, b, c, d;
vector<pair<int, int>> edges;
map<pair<int, int>, int> edge_id;
ll w[N * 2];
bool is_vip[N * 2];

vector<int> dijkstra_path(int src, int dst, ll* cost) {
    vector<ll> dist(n + 1, INF);
    vector<int> prev(n + 1, -1);
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<>> pq;
    dist[src] = 0;
    pq.push({0, src});
    while (!pq.empty()) {
        auto [d, u] = pq.top(); pq.pop();
        if (d > dist[u]) continue;
        for (auto [v, eid] : adj[u]) {
            ll c = cost[eid];
            if (dist[v] > dist[u] + c) {
                dist[v] = dist[u] + c;
                prev[v] = u;
                pq.push({dist[v], v});
            }
        }
    }
    vector<int> path;
    int cur = dst;
    while (cur != -1) {
        path.push_back(cur);
        cur = prev[cur];
    }
    reverse(path.begin(), path.end());
    return path;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n >> m >> a >> b >> c >> d;
    for (int i = 1; i <= m; i++) {
        int u, v; ll ww;
        cin >> u >> v >> ww;
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
        edges.push_back({u, v});
        edge_id[{u, v}] = i;
        edge_id[{v, u}] = i;
        w[i] = ww;
    }
    ll cost1[N * 2];
    for (int i = 1; i <= m; i++) cost1[i] = w[i];
    vector<int> path = dijkstra_path(a, b, cost1);
    for (int i = 1; i < path.size(); i++) {
        int u = path[i - 1], v = path[i];
        int eid = edge_id[{u, v}];
        is_vip[eid] = true;
    }
    ll cost2[N * 2];
    for (int i = 1; i <= m; i++) cost2[i] = is_vip[i] ? 0 : w[i];
    vector<ll> dist(n + 1, INF);
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<>> pq;
    dist[c] = 0;
    pq.push({0, c});
    while (!pq.empty()) {
        auto [d, u] = pq.top(); pq.pop();
        if (d > dist[u]) continue;
        for (auto [v, eid] : adj[u]) {
            ll c = cost2[eid];
            if (dist[v] > dist[u] + c) {
                dist[v] = dist[u] + c;
                pq.push({dist[v], v});
            }
        }
    }
    cout << dist[d] << endl;
    return 0;
}

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