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  1. #include <iostream>
  2. #include <bits/stdc++.h>
  3. using namespace std;
  4. void fast()
  5. {
  6.     ios_base::sync_with_stdio(false);
  7.     cin.tie(NULL);
  8.     cout.tie(NULL);
  9. }
  10. const int n=8e+5;
  11. int t,s;
  12. vector<int>v[n];
  13. int visited[n];
  14. void dfs(int node)
  15. {
  16.     visited[node];
  17.     for(int child:v[node])
  18.     {
  19.         if(!visited[child])dfs(child);
  20.     }
  21.  
  22. }
  23.  
  24. int main()
  25. {
  26.     fast();
  27.     cin>>t>>s;
  28.     for(int i=0;i<s;i++)
  29.     {
  30.         int a,b;
  31.         cin>>a>>b;
  32.         v[a].push_back(b);
  33.         v[b].push_back(a);
  34.     }
  35.     int c=0;
  36.     for(int i=1; i<=t; i++)
  37.     {
  38.         if(!visited[i])
  39.         {
  40.             c++;
  41.             dfs(i);
  42.         }
  43.     }
  44.     if(c==1&&s==(t-1))cout<<"YES";
  45.     else cout<<"NO";
  46.  
  47.     return 0;
  48. }
Success #stdin #stdout 0.01s 23688KB
comments (?)
stdin
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Standard input is empty
stdout
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NO
https://ideone.com/hWt1VG
language:
C++ (gcc 8.3)
created:
1 year ago
visibility:
public

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