Submission #857577

#	Time	Username	Problem	Language	Result	Execution time	Memory
857577		dio_2	Commuter Pass (JOI18_commuter_pass)	C++17	15 / 100	137 ms	13732 KiB

commuter_pass

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

const long long inf = (long long)1e18;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int n, m, s, t, u, v;
	cin >> n >> m >> s >> t >> u >> v;
	
	vector<vector<pair<int, int>>> adj(n + 1);
	
	while(m--){
		int a, b, c;
		cin >> a >> b >> c;
		adj[a].emplace_back(b, c);
		adj[b].emplace_back(a, c);
	}
	
	auto Do = [&](int src, vector<long long> &d)->void{
      fill(d.begin(), d.end(), inf);
      vector<bool> in_Q(n + 1);
      d[src] = 0;
      priority_queue<pair<long long, int>> pq;
      pq.push({0, src});
      while(!pq.empty()){
			auto [_, node] = pq.top();		
			pq.pop();
			if(in_Q[node]) continue;
			in_Q[node] = 1;
			for(auto [to, cost] : adj[node]){
				if(d[node] + cost < d[to]){
					d[to] = d[node] + cost;
					pq.push({-d[to], to});
				}
			}
	   }
	};
	
	vector<long long> D1(n + 1);
	Do(s, D1);
	
	int cr = t;
	bool unique = 1;
	
	while(cr != s){ // making the edges in the SP free.
		int cnt = 0;
		for(auto &[node, cost] : adj[cr]){
			if(D1[node] + cost == D1[cr]){
				cost = 0;
				for(auto &[node2, cost2] : adj[node]){
					if(node2 == cr){
						cost2 = 0;
					}
				}
				cr = node;
				++cnt;
				unique &= (cnt == 1);
			}
		}
	}
	
	if(unique){
		vector<long long> Du(n + 1);
		Do(u, Du);
		
		cout << Du[v] << '\n';
		return 0;
	}
	return 0;
}

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