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  1. #include <iostream>
  2. using namespace std;
  3. #include <bits/stdc++.h>
  4.  
  5. int main() {
  6. 	// your code goes here
  7. 	int n,m;
  8. 	cin>>n>>m;
  9. 	vector<int>b[n+5];
  10. 	int i=1;
  11. 	for(i=1;i<=m;i++)
  12. 	 {
  13. 	 	int x,y;
  14. 	 	cin>>x>>y;
  15. 	 	b[x].push_back(y);
  16. 	 	b[y].push_back(x);
  17. 	 }
  18.  
  19. 	 int source = 1;
  20. 	 int used[n+5]={0};
  21. 	 int level[n+5]={-1};
  22. 	 queue<int>q;
  23. 	 q.push(source);
  24. 	 used[source]=1;
  25. 	 level[source]=0;
  26.  
  27. 	 while(!q.empty())
  28. 	  {
  29. 	  	int removed;
  30. 	  	removed=q.front();
  31. 	  	q.pop();
  32.  
  33. 	  	for(auto x:b[removed])
  34. 	  	 {
  35. 	  	 	if(used[x]==0)
  36. 	  	 	 {
  37. 	  	 	 	q.push(x);
  38. 	  	 	 	used[x]=1;
  39. 	  	 	 	level[x]=level[removed]+1;
  40. 	  	 	 }
  41. 	  	 }
  42.  
  43.  
  44. 	  }
  45.  
  46. 	  	 i=1;
  47. 	  	 while(i<=n)
  48. 	  	  {
  49. 	  	  	if(used[i]==0)
  50. 	  	  	 {
  51. 	  	  	 	cout<<"you cannot reach node "<<i<<" to source node "<<source<<endl;
  52. 	  	  	 }
  53. 	  	  	 else
  54. 	  	  	 {
  55. 	  	  	 	cout<<"you can reach node "<<i<<" to source node "<<source<<endl;
  56. 	  	  	 }
  57. 	  	  	//cout<<i<<"-"<<level[i]<<endl;
  58. 	  	    i++;
  59.  
  60. 	  	  }
  61.  
  62.  
  63.  
  64.  
  65.  
  66.  
  67.  
  68.  
  69. 	return 0;
  70. }
Success #stdin #stdout 0s 5288KB
comments (?)
stdin
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7 7
1 2
1 3
1 4
2 5
3 5
3 6
4 6
stdout
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you can reach node 1 to source node 1
you can reach node 2 to source node 1
you can reach node 3 to source node 1
you can reach node 4 to source node 1
you can reach node 5 to source node 1
you can reach node 6 to source node 1
you cannot reach node 7 to source node 1
https://ideone.com/VKcSLg
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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