Submission #782882

#	Time	Username	Problem	Language	Result	Execution time	Memory
782882		acatmeowmeow	Commuter Pass (JOI18_commuter_pass)	C++11	100 / 100	238 ms	27160 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;

#define int long long 

const int N = 2e5 + 5;
int n, m, s, t, u, v, f[N], se[N], mn[N], mn2[N], ans[N], dist[N];
vector<pair<int, int>> adj[N];

void path(int s, int dist[]) {
	dist[s] = 0;
	priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
	pq.push({0, s});
	while (pq.size()) {
	    int	p = pq.top().first, u = pq.top().second;
		pq.pop();
		if (p != dist[u]) continue;
		for (auto&x : adj[u]) {
			int v = x.first, c = x.second;
			if (dist[v] <= dist[u] + c) continue;
			dist[v] = dist[u] + c;
			pq.push({dist[v], v});
		}
	}
}

void solve() {
	for (int i = 1; i <= n; i++) dist[i] = mn[i] = mn2[i] = ans[i] = 1e18;
	dist[s] = 0;
	priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
	pq.push({0, s});
	while (pq.size()) {
	    int	p = pq.top().first, u = pq.top().second;
		pq.pop();
		if (p != dist[u]) continue;
		mn[u] = min(mn[u], f[u]);
		mn2[u] = min(mn2[u], se[u]);
		for (auto&x : adj[u]) {
			int v = x.first, c = x.second;
			if (dist[v] + c == dist[u]) {
				mn[u] = min(mn[u], mn[v]);
				mn2[u] = min(mn2[u], mn2[v]);
				ans[u] = min(ans[u], ans[v]);
			} else if (dist[v] > dist[u] + c) {
				dist[v] = dist[u] + c;
				pq.push({dist[v], v});
			}
		}
		ans[u] = min({ans[u], se[u] + mn[u], f[u] + mn2[u]});
	}
	cout << min({ans[t], f[v]}) << '\n';
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> n >> m >> s >> t >> u >> v;
	for (int i = 1;i <= m; i++) {
		int u, v, c;
		cin >> u >> v >> c;
		adj[u].push_back({v, c});
		adj[v].push_back({u, c});
	}
	for (int i = 1;i <= n; i++) f[i] = se[i] = 1e18;
	path(u, f);
   	path(v, se);
	solve();
	return 0;
}

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