fork download
copy 
  1. #include <iostream>
  2. #include <vector>
  3. #include <utility>
  4. #include <queue>
  5.  
  6. using namespace std;
  7.  
  8. int main() {
  9. 	int n, m, i;
  10. 	cin >> n >> m;
  11.  
  12. 	vector<pair<int, int>> games(m);
  13.  
  14. 	int u, v, t;
  15. 	for (i = 0; i < m; i++) {
  16. 		cin >> u >> v >> t;
  17. 		if (t == 1) games[i] = make_pair(u-1, v-1);
  18. 		else games[i] = make_pair(v-1, u-1);
  19. 	}
  20.  
  21. 	vector<vector<int>> graph(n, vector<int> {});
  22. 	for (auto j: games) graph[j.first].push_back(j.second);
  23.  
  24. 	vector<int> indeg(n);
  25. 	for (auto j: games) indeg[j.second]++;
  26.  
  27. 	int processed = 0;
  28. 	bool flag = true;
  29. 	queue<int> q;
  30. 	for (i = 0; i < n; i++)
  31. 		if (indeg[i] == 0) q.push(i);
  32.  
  33. 	while (!q.empty()) {
  34. 		if (q.size() > 1) flag=false;
  35. 		u = q.front();
  36. 		q.pop();
  37.  
  38. 		for (auto v: graph[u]) {
  39. 			indeg[v]--;
  40. 			if (indeg[v] == 0) q.push(v);
  41. 		}
  42. 		processed++;
  43. 	}
  44.  
  45. 	if (flag) cout << "YES\n";
  46. 	else cout << "NO\n";
  47. }
Success #stdin #stdout 0.01s 5320KB
comments (?)
stdin
copy 
5 2
2 4 2
3 2 1
stdout
copy 
NO
https://ideone.com/QYPC6M
language:
C++14 (gcc 8.3)
created:
7 hours ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!