Submission #388679

#	Time	Username	Problem	Language	Result	Execution time	Memory
388679		Vlatko	Commuter Pass (JOI18_commuter_pass)	C++14	31 / 100	338 ms	20160 KiB

commuter_pass

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

using ll = long long;
using pli = pair<ll, int>;

const ll inf = 1e18;
const int N = 100100;

int n, m, S, T, U, V;
vector<pli> adj[N];

ll ans;

ll dU[N];
ll dV[N];

ll dS[N];
ll mdU[N];
ll mdV[N];

void dijkstra(int source, ll dist[N]) {
	priority_queue<pli, vector<pli>, greater<pli>> pq;
	for (int i = 1; i <= n; ++i) {
		dist[i] = inf;
	}
	dist[source] = 0;
	pq.emplace(0, source);
	while (!pq.empty()) {
		ll d, w;
		int u, v;
		tie(d, u) = pq.top();
		pq.pop();
		if (d != dist[u]) continue;
		for (pli to : adj[u]) {
			tie(w, v) = to;
			if (d + w < dist[v]) {
				dist[v] = d + w;
				pq.emplace(dist[v], v);
			}
		}
	}
}

void dijkstra2() {
	priority_queue<pli, vector<pli>, greater<pli>> pq;
	for (int i = 1; i <= n; ++i) {
		dS[i] = inf;
	}
	dS[S] = 0;
	mdU[S] = dU[S];
	mdV[S] = dV[S];
	pq.emplace(0, S);
	while (!pq.empty()) {
		ll d, w;
		int a, b;
		tie(d, a) = pq.top();
		pq.pop();
		if (d != dS[a]) continue;
		for (pli to : adj[a]) {
			// a -> b
			tie(w, b) = to;
			if (d + w < dS[b]) {
				dS[b] = d + w;
				mdU[b] = min(mdU[a], dU[b]);
				mdV[b] = min(mdV[a], dV[b]);
				pq.emplace(dS[b], b);
			} else if (d + w == dS[b]) {
				mdU[b] = min(mdU[b], mdU[a]);
				mdV[b] = min(mdV[b], mdV[a]);
			}
		}
	}
}

int main() {
	cin.tie(0)->sync_with_stdio(false);
//	#ifndef _DEBUG
//	freopen("piepie.in", "r", stdin);
//	freopen("piepie.out", "w", stdout);
//	#endif
	cin >> n >> m >> S >> T >> U >> V;
	for (int i = 0; i < m; ++i) {
		int a, b, w;
		cin >> a >> b >> w;
		adj[a].emplace_back(w, b);
		adj[b].emplace_back(w, a);
	}
	dijkstra(U, dU);
	dijkstra(V, dV);
	dijkstra2();
	ans = min(dU[V], dV[U]);
	ans = min(ans, mdU[T] + mdV[T]);
	cout << ans << '\n';
}

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