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  1. #include <iostream>
  2. #include <cstdio>
  3. #include <vector>
  4.  
  5. #define MAXN 1024
  6.  
  7. using namespace std;
  8.  
  9. int N, M, start;
  10. vector<int> G[MAXN];
  11.  
  12. void read()
  13. {
  14. 	cin >> N >> M;
  15.  
  16. 	for(int i = 0; i < M; i++)
  17. 	{
  18. 		int u, v;
  19. 		cin >> u >> v;
  20.  
  21. 		G[u].push_back(v);
  22. 		G[v].push_back(u);
  23. 	}
  24.  
  25. 	cin >> start;
  26. }
  27.  
  28. int used[MAXN];
  29. bool visited[MAXN];
  30.  
  31. void DFS(int u, int level, int parent)
  32. {
  33. 	used[u] = level;
  34. 	visited[u] = true;
  35.  
  36. 	int sz = G[u].size();
  37. 	for(int i = 0; i < sz; i++)
  38. 	{
  39. 		int v = G[u][i];
  40.  
  41. 		if(!visited[v])
  42. 			DFS(v, level + 1, u);
  43.  
  44. 		if(v != parent && used[v] != 0)
  45. 			cout << "Length of Cycle from " << v << " to " << u << " is " << level - used[v] + 1 << endl;
  46. 	}
  47.  
  48. 	used[u] = 0;
  49. }
  50.  
  51. void solve()
  52. {
  53. 	DFS(start, 1, -1);	
  54. }
  55.  
  56. int main()
  57. {
  58. 	ios_base::sync_with_stdio(false);
  59. 	cin.tie(NULL);
  60.  
  61. 	read();
  62. 	solve();
  63. 	return 0;
  64. }
  65.  
Success #stdin #stdout 0s 3296KB
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https://ideone.com/RXOWWP
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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