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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. typedef long long int ll;
  5. #define IOS ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  6.  
  7. typedef pair<int,int>pr;
  8. #define all(i) i.begin() , i.end()
  9. #define ft first
  10. #define sn second
  11. #define pb push_back
  12.  
  13. const int mod = 1e9+7;
  14. #define en "\n"
  15. #define dbg cout<<"rony\n";
  16.  
  17. vector<int>g[30];
  18. int vis[30];
  19. #define MAXN 200010
  20. vector<pair<int,int>>v;
  21.  
  22. void dfs(int nd)
  23. {
  24.  vis[nd] = 1;
  25.  for(auto i:g[nd])
  26.  {
  27.  if(vis[i] == 1) continue;
  28.  v.pb({i,nd});
  29.  dfs(i);
  30.  }
  31. }
  32. void solve()
  33. {
  34.  int n;
  35.  cin >> n;
  36.  string s,t;
  37.  cin >> s >> t;
  38.  map<pair<char,char>,int>ma;
  39.  
  40.  for(int i = 0;i < n;i++)
  41.  {
  42.  if(s[i] == t[i]) continue;
  43.  char c = max(s[i],t[i]);
  44.  char d = min(s[i],t[i]);
  45.  if(ma[{d,c}] == 1) continue;
  46.  
  47.  ma[{d,c}]++;
  48.  g[s[i]-'a'].pb(t[i]-'a');
  49.  g[t[i]-'a'].pb(s[i] - 'a');
  50.  }
  51.  
  52.  for(int i = 0;i < 26;i++)
  53.  {
  54.  if(vis[i] == 0 && g[i].size() > 0)
  55.  {
  56.  dfs(i);
  57.  }
  58.  }
  59.  
  60.  cout<<v.size()<<en;
  61.  for(auto i:v)
  62.  {
  63.  char c = i.ft + 'a';
  64.  char d = i.sn + 'a';
  65.  cout<<c<<" "<<d<<en;
  66.  }
  67. } 
  68.  
  69. int main()
  70. {
  71.  IOS;
  72.  int t;
  73.  //cin >> t;
  74.  t = 1;
  75.  while ( t-- )
  76.  {
  77.  
  78.  solve();
  79.  }
  80.  return 0;
  81. }
Success #stdin #stdout 0.01s 5460KB
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https://ideone.com/m2HEJv
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
secret

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