Submission #1032244

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032244		belgianbot	Commuter Pass (JOI18_commuter_pass)	C++17	0 / 100	2084 ms	262144 KiB

commuter_pass

#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second

using namespace std;

ll MAX = 1e14 * 2;
int N, M, S, T, U, V;
vector<vector<pair<int,ll>>> adj;
vector<vector<int>> trajects;
vector<bool> processed;
vector<ll> memo;

ll dp (int pos) {
	if (pos == T) return memo[pos] = 0;
	
	if (memo[pos] != -1) return memo[pos];
	processed[pos] = true;
	
	ll ans = MAX + 1;
	for (auto x : adj[pos]) {
		if (!processed[x.fi]) {
			ans = min(ans, dp(x.fi) + x.se);
		}
	}
	
	processed[pos] = false;
	if (ans <= MAX) return memo[pos] = ans;
	else return ans;
}

void res(int pos, ll cost, vector<int> *current) {
	if (pos == T) {
		return;
	}
		
	vector<int> copy = *current;
	processed[pos] = true;
	bool already = false;
	for (auto x : adj[pos]) {
		if (!processed[x.fi]) {
			if (memo[x.fi] + x.se + cost == memo[S]) {
				if (already) {
					trajects.push_back({});
					trajects.back() = copy;
					trajects.back().push_back(x.fi);
					res(x.fi, cost + x.se, &trajects.back());
				}
				else {
					current->push_back(x.fi);
					res(x.fi, cost + x.se, current);
					already = true;
				}
			}
		}
	}
	processed[pos] = false;
}
				
		
			
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> N >> M >> S >> T >> U >> V;
	S--, T--, U--, V--;
	
	adj.resize(N); memo.resize(N, -1); processed.resize(N, false);
	for (int i = 0; i < M; i++) {
		int a, b; ll c; cin >> a >> b >> c;
		a--, b--;
		adj[a].push_back({b,c});
		adj[b].push_back({a,c});
	}
	
	dp(S);
	trajects.push_back({S});
	res(S, 0, &trajects.back());
	
	vector<ll> distU(N, MAX), distV(N, MAX);
	priority_queue < pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll,int>>> q;
	q.push({0,U}); distU[U] = 0;
	
	while (!q.empty()) {
		int x = q.top().se; q.pop();
		if (processed[x]) continue;
		
		processed[x] = true;
		for (auto w : adj[x]) {
			if (distU[w.fi] > distU[x] + w.se) {
				distU[w.fi] = distU[x] + w.se;
				q.push({distU[w.fi], w.fi});
			}
		}
	}
	
	processed.clear(); processed.resize(N, false);
	q.push({0, V}); distV[V] = 0;
	
	while (!q.empty()) {
		int x = q.top().se; q.pop();
		if (processed[x]) continue;
		
		processed[x] = true;
		for (auto w : adj[x]) {
			if (distV[w.fi] > distV[x] + w.se) {
				distV[w.fi] = distV[x] + w.se;
				q.push({distV[w.fi], w.fi});
			}
		}
	}
	
	ll ans = distU[V];
	for (auto x : trajects) {
		ll miniU = MAX, miniV = MAX;
		for (int y : x) {
			miniU = min(miniU, distU[y]);
			miniV = min(miniV, distV[y]);
			ans = min(ans, miniV + miniU);
		}
	}
	cout << ans << '\n';
		
	return 0;
}
	

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