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  1. #include <iostream>
  2. #include<bits/stdc++.h>
  3.  
  4. using namespace std;
  5.  
  6. int n,m;
  7.  
  8. void prov(int i,vector<vector<int>> &adj,vector<int> &visit)
  9. {
  10. 	if(visit[i])return;
  11.  
  12. 	visit[i]=true;
  13.  
  14. 	for(auto x: adj[i])
  15. 	{
  16. 		prov(x,adj,visit);
  17. 	}
  18.  
  19. 	return;
  20. }
  21.  
  22. int main() {
  23.  
  24. 	cin>>n>>m;
  25.  
  26.  
  27. 	vector<int> visit (n+1,0);
  28.  
  29. 	vector<vector<int>>adj(n+1);
  30.  
  31. 	vector<vector<int>>arr(m, vector<int>(2));
  32.  
  33. 	for(int i=0;i<m;i++)
  34. 	{
  35.  
  36. 		cin>>arr[i][0]>>arr[i][1];
  37.  
  38. 	}
  39.  
  40. 	for(int i=0;i<m;i++)
  41. 	{
  42. 		adj[arr[i][0]].push_back(arr[i][1]);
  43. 		adj[arr[i][1]].push_back(arr[i][0]);
  44. 	}
  45.  
  46. 	int count=0;
  47. 	vector<int>city;
  48.  
  49. 	for(int i=1;i<n;i++)
  50. 	{
  51. 		if(!visit[i])
  52. 		{
  53. 			count++;
  54. 			prov(i,adj,visit);
  55. 			city.push_back(i);
  56. 		}
  57. 	}
  58.  
  59. 	cout<< count-m<<endl;
  60.  
  61. 	for(int i=0;i<city.size()-1;i++)
  62. 	{
  63. 		cout<<city[i]<<city[i+1]<<endl;
  64. 	}
  65. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/WAiqqw
language:
C++14 (gcc 8.3)
created:
7 days ago
visibility:
public

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