Submission #782804

#	Time	Username	Problem	Language	Result	Execution time	Memory
782804		acatmeowmeow	Commuter Pass (JOI18_commuter_pass)	C++11	15 / 100	865 ms	262144 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;

//#define int long long 

vector<long long> path(int n, int s, vector<vector<pair<int, long long>>>&adj) {
	vector<long long> dist(n + 5, 1e18);
	dist[s] = 0;
	priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> pq;
	pq.push({0, s});
	while (pq.size()) {
		long long p = pq.top().first;
	    int	u = pq.top().second;
		pq.pop();
		if (p != dist[u]) continue;
		for (auto&x : adj[u]) {
			int v = x.first;
		   	long long c = x.second;
			if (dist[v] < dist[u] + c) continue;
			dist[v] = dist[u] + c;
			pq.push({dist[v], v});
		}
	}
	return dist;
}

void solve(int n, int s, int t, int u, int v, vector<vector<pair<int, long long>>>&adj, vector<long long>&f, vector<long long>&se) {
	//vector<long long> dist(n + 5, 1e18), mn(n + 5, 1e18), ans(n + 5, 1e18), mn2(n + 5, 1e18);
	long long dist[n + 5], mn[n + 5], mn2[n + 5], ans[n + 5];
	for (int i = 1; i <= n; i++) dist[i] = mn[i] = mn2[i] = ans[i] = 1e18;
	dist[s] = 0;
	priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> pq;
	pq.push({0, s});
	while (pq.size()) {
		long long p = pq.top().first;
	    int	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;
		   	long long c = x.second;
			if (dist[v] + c != dist[u]) continue;
			mn[u] = min(mn[u], mn[v]);
			mn2[u] = min(mn2[u], mn2[v]);
			ans[u] = min(ans[u], ans[v]);
		}
		ans[u] = min({ans[u], se[u] + mn[u], f[u] + mn2[u]});
		if (u == t) break;
		for (auto&x : adj[u]) {
			int v = x.first;
		  	long long c = x.second;
			if (dist[v] < dist[u] + c) continue;
			dist[v] = dist[u] + c;
			pq.push({dist[v], v});
		}
	}
	cout << min({ans[t], f[v]}) << '\n';
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n, m;
	cin >> n >> m;
	int s, t;
	cin >> s >> t;
	int u, v;
	cin >> u >> v;
	vector<vector<pair<int, long long>>> adj(n + 5);
	for (int i = 1;i <= m; i++) {
		int u, v;
	   	long long c;
		cin >> u >> v >> c;
		adj[u].push_back({v, c});
		adj[v].push_back({u, c});
	}
	vector<long long> f = path(n, u, adj), se = path(n, v, adj);
	solve(n, s, t, u, v, adj, f, se);
	return 0;
}

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