제출 #448373

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
448373		training4usaco	Commuter Pass (JOI18_commuter_pass)	C++11	100 / 100	620 ms	31396 KiB

commuter_pass

#include <iostream>
#include <vector>
#include <queue>
using namespace std;

using ll = long long;
using pll = pair<ll, ll>;
 
#define MAXN 100001
#define INF 4600000000000000000

ll n, m, s, t, u, v;
vector<vector<pll>> adj(MAXN);
vector<ll> distu(MAXN), distv(MAXN), dists(MAXN);
vector<vector<ll>> dp(2, vector<ll>(MAXN));
ll answer;
vector<bool> visited(MAXN, false);
 
void dijkstra1(ll start, vector<ll>& dist) {
	visited = vector<bool>(MAXN, false);
 
	priority_queue<pll, vector<pll>, greater<pll>> pq;

	pq.push({0, start});
	while (!pq.empty()) {
		ll cdist = pq.top().first;
		ll node = pq.top().second;
		pq.pop();
 
		if (!visited[node]) {
			dist[node] = cdist;
			visited[node] = true;
			for (auto i : adj[node]) {
                pq.push({cdist + i.second, i.first});
            }
		}
	}
}
 
void dijkstra2(ll start, ll end) {
    dp[0] = vector<ll>(MAXN, INF);
    dp[1] = vector<ll>(MAXN, INF);
	visited = vector<bool>(MAXN, false);
 
	priority_queue<pair<ll, pll>, vector<pair<ll, pll>>, greater<pair<ll, pll>>> pq;
	pq.push({0, {start, 0}});

    dp[0][0] = INF;
    dp[1][0] = INF;
	while (!pq.empty()) {
		ll cdist = pq.top().first;
        ll node = pq.top().second.first;
        ll par = pq.top().second.second;
		pq.pop();
 
		if (!visited[node]) {
			visited[node] = true;
			dists[node] = cdist;
			dp[0][node] = min(distu[node], dp[0][par]);
			dp[1][node] = min(distv[node], dp[1][par]);

			for (auto i : adj[node]) {
                pq.push({cdist + i.second, {i.first, node}});
            }
		} 
        else if (cdist == dists[node]) {
			if (min(distu[node], dp[0][par]) + min(distv[node], dp[1][par]) <= dp[0][node] + dp[1][node]) {
				dp[0][node] = min(distu[node], dp[0][par]);
				dp[1][node] = min(distv[node], dp[1][par]);
			}
		}
	}
 
	answer = min(answer, dp[0][end] + dp[1][end]);
}
 
int main() {
	cin >> n >> m >> s >> t >> u >> v;

	for (int i = 0; i < m; i++) {
		ll a, b, cdist;
		cin >> a >> b >> cdist;
		adj[a].push_back({b, cdist});
		adj[b].push_back({a, cdist});
	}
 
	dijkstra1(u, distu);
	dijkstra1(v, distv);
 
	answer = distu[v];
 
	dijkstra2(s, t);
 
	cout << answer << endl;
	return 0;
}

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