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  1. #include <bits/stdc++.h>
  2. using namespace std; 
  3. #define endl '\n'
  4. #define ll long long int
  5. #define ull unsigned long long int
  6. #define ld long double
  7. #define loop(a,b,c) for(ll i=a;i<=b;i+=c)
  8. #define intarr(arr,n) ll arr[n];for(ll i=0;i<n;i++)cin>>arr[i]
  9. #define inparr(arr,n) for(ll i=0;i<n;i++)cin>>arr[i]
  10. #define inpvec(vec,n) for(ll i=0;i<n;i++){ll var;cin>>var;vec.push_back(var);}
  11. #define pb push_back
  12. #define fastio ios_base::sync_with_stdio(false);cin.tie(NULL);
  13. #define mod 1000000007
  14. #define newline cout<<endl
  15. #define ump unordered_map<ll,ll>
  16. #define vec vector<ll>
  17. #define mkp make_pair
  18. #define disp(var1,var2) cout<<var1<<" "<<var2<<endl;
  19. #define all(v)             v.begin(),v.end()
  20. #define cout(var) cout<<var<<endl
  21. #define p 998244353
  22. #define teensort(a,r,g,b) a[0]=r;a[1]=g;a[2]=b;sort(a,a+3);
  23. ll a[200005];
  24. void AcDegaYe()
  25. {
  26.     ll n,k;
  27.     cin>>n>>k;
  28.     k=min(k,n);
  29.     for(ll i=0;i<n;i++)
  30.         cin>>a[i];
  31.     list<ll> v;
  32.     ump h;
  33.     for(ll i=0;i<n;i++)
  34.     {
  35.         if(v.size()<k)
  36.         {
  37.             if(h.count(a[i])==0)
  38.             {
  39.                 v.push_front(a[i]);
  40.                 h[a[i]]=1;
  41.             }
  42.             else
  43.                 continue;
  44.         }
  45.         else
  46.         {
  47.             if(h.count(a[i])==1)
  48.             {
  49.                 continue;
  50.             }
  51.             else
  52.             {
  53.                 h.erase(v.back());
  54.                 v.pop_back();
  55.                 v.push_front(a[i]);
  56.                 h[a[i]]=1;
  57.  
  58.             }
  59.         }
  60.     }
  61.     cout(v.size());
  62.     for(auto it:v)
  63.     {
  64.         cout<<it<<" ";
  65.     }
  66.     cout<<endl;
  67. }
  68.  
  69.  
  70. int main()
  71. {   
  72.     fastio
  73.     //ll t;
  74.     //cin>>t;
  75.     ll t=1;
  76.     while(t--)
  77.     {
  78.         AcDegaYe();
  79.     }
  80.     cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
  81.     return 0;
  82. }
Success #stdin #stdout #stderr 0s 4300KB
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Time elapsed: 3ms
https://ideone.com/Dn2nQN
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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