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  1. #include <bits/stdc++.h>
  2. #define pb push_back 
  3. #define pii pair<int,int> 
  4. #define endl "\n"
  5. #define vi vector<int>
  6. #define io ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
  7. using namespace std;
  8.  
  9. vi parent;
  10. int n,m;
  11.  
  12. inline void init(){
  13.     parent.resize(n+2);
  14.  
  15.     for(int i=1;i<=n;i++){
  16.         parent[i]=i;
  17.     }
  18. }
  19.  
  20.  
  21. inline int findtree(int k){
  22.     if(k==parent[k])return k;
  23.     else{
  24.         int root=findtree(parent[k]);
  25.         parent[k]=root;
  26.         return root;
  27.     }
  28. }
  29.  
  30. inline void merge(int x,int y){
  31.     x=findtree(x),y=findtree(y);
  32.     if(x!=y){
  33.         if(x<y)swap(x,y);
  34.         parent[x]=y;
  35.     }
  36. }
  37.  
  38. int main(){
  39.     io
  40.     while(cin>>n>>m){
  41.     	init();
  42.     	int x,y;
  43.     	for(int i=0;i<m;i++){
  44.     	   cin>>x>>y;
  45.     	    merge(x,y);
  46.     	}
  47.     	int k;cin>>k;
  48.     	cout<<findtree(k)<<endl;
  49.     }
  50.  
  51.     return 0;
  52. }
  53.  
Success #stdin #stdout 0s 5496KB
comments (?)
stdin 
10 6
1 2
3 6
2 7
6 7
4 5
5 8
3
stdout 
1
1 1 1 4 4 3 1 4 9 10
https://ideone.com/BzdRQN
language:
C++ (gcc 8.3)
created:
2 years ago
visibility:
public

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