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  1. /*Chu trinh tren do thi vo huong*/
  2.  
  3. #include <bits/stdc++.h>
  4. using namespace std;
  5.  
  6. int n, m, st, en;
  7. vector<int> adj[1001];
  8. bool visited[1001];
  9. int parent[1001];
  10.  
  11. void inp(){
  12. 	cin >> n >> m;
  13. 	for(int i = 0; i < m; i++){
  14. 		int x, y; cin >> x >> y;
  15. 		adj[x].push_back(y);
  16. 		adj[y].push_back(x);
  17. 	}
  18. 	memset(visited, false, sizeof(visited));
  19. }
  20.  
  21.  
  22. bool DFS(int u){
  23. 	visited[u] = true;
  24. 	for(int v : adj[u]){
  25. 		if(!visited[v]){
  26. 			parent[v] = u;
  27. 			if(DFS(v)) return true;
  28. 		}
  29. 		else if(v != parent[u]){
  30. 			return true;
  31. 		}
  32. 	}
  33. 	return false;
  34. }
  35.  
  36. bool BFS(int u){
  37. 	visited[u] = true;
  38. 	queue<int> q;
  39. 	q.push(u);
  40. 	while(! q.empty()){
  41. 		int v = q.front(); q.pop();
  42. 		for(int x : adj[v]){
  43. 			if(!visited[x]){
  44. 				q.push(x); visited[x] = true; parent[x] = v;
  45. 			}
  46. 			else if(x != parent[v]){
  47. 				return true;
  48. 			}
  49. 		}
  50. 	}
  51. 	return false;
  52. }
  53.  
  54.  
  55. int main(){
  56. 	inp();
  57. 	for(int i = 1; i <= n; i++){
  58. 		if(!visited[i]){
  59. 			if(DFS(i)){
  60. 				cout << "YES\n";
  61. 				return 0;
  62. 			}
  63. 		}
  64. 	}
  65. 	cout << "NO\n";
  66. 	return 0;
  67. }
  68.  
Success #stdin #stdout 0.01s 5288KB
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stdin
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Standard input is empty
stdout
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NO
https://ideone.com/KM6Cn0
language:
C++14 (gcc 8.3)
created:
5 hours ago
visibility:
public

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