Submission #852250

#	Time	Username	Problem	Language	Result	Execution time	Memory
852250		Calico	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	826 ms	155552 KiB

commuter_pass

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

#define int long long
const int INF = 1e18;

vector<int> dijkstra(int n, vector<tuple<int, int, int>> edges, int src) {
	vector<vector<pair<int, int>>> g(n);
	for (auto [x, y, w]: edges) {
		g[x].emplace_back(y, w);
	}

	vector<int> dist(n, INF);
	priority_queue<pair<int, int>> pq;
	pq.push({0, src}); dist[src] = 0;

	while (pq.size()) {
		auto [ds, u] = pq.top(); pq.pop();
		if (dist[u] != -ds) continue;

		for (auto [v, w]: g[u]) {
			if (dist[v] > dist[u]+w) {
				dist[v] = dist[u]+w;
				pq.push({-dist[v], v});
			}
		}
	}

	return dist;
}

signed main() {
	ios::sync_with_stdio(0); cin.tie(0);

	int n, m, s, t, u, v;
	cin >> n >> m >> s >> t >> u >> v;
	s--, t--, u--, v--;

	vector<tuple<int, int, int>> g1;
	for (int i = 0; i < m; i++) {
		int x, y, w; cin >> x >> y >> w; x--, y--;
		g1.emplace_back(x, y, w);
		g1.emplace_back(y, x, w);
	}

	vector<int> dists = dijkstra(n, g1, s);
	vector<int> distt = dijkstra(n, g1, t);

	vector<tuple<int, int, int>> g2;
	for (int i = 0; i < n; i++) {
		g2.emplace_back(i, n+i, 0);
		g2.emplace_back(i, 2*n+i, 0);

		g2.emplace_back(n+i, 3*n+i, 0);
		g2.emplace_back(2*n+i, 3*n+i, 0);
	}
	for (auto [x, y, w]: g1) {
		g2.emplace_back(x, y, w);
		g2.emplace_back(3*n+x, 3*n+y, w);

		if (dists[x]+distt[y]+w == dists[t]) {
			g2.emplace_back(n+x, n+y, 0);
			g2.emplace_back(2*n+y, 2*n+x, 0);
		}
	}

	vector<int> ans = dijkstra(4*n, g2, u);
	cout << ans[3*n+v] << '\n';
	
	return 0;
}

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