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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. using namespace std;
  5.  
  6. bool is_prime( int z, vector < int > P )
  7. {
  8.     bool ip = true;
  9.     for ( int i = 0; P[ i ] * P[ i ] <= z && ip; ++i )
  10.         ip = ip && ( z % P[ i ] != 0 );
  11.     return ip;
  12. }
  13.  
  14. int mega_prime( int index )
  15. {
  16.     vector < int > MP, P;
  17.     P.push_back( 2 );
  18.     for ( int x = 3; index > ( int )MP.size(); x += 2 )
  19.     {
  20.         if ( is_prime( x, P ) )
  21.         {
  22. 	    P.push_back( x );       
  23.             if ( is_prime( ( int )P.size(), P ) )
  24. 	        MP.push_back( x );
  25.         }
  26.     }
  27.     return MP.back();
  28. }
  29.  
  30. int main()
  31. {
  32.     cout << mega_prime( 1 ) << endl;
  33.     cout << mega_prime( 2 ) << endl;
  34.     cout << mega_prime( 3 ) << endl;
  35.     cout << mega_prime( 5 ) << endl;
  36.     cout << mega_prime( 10 ) << endl;
  37. }
Success #stdin #stdout 0.01s 2860KB
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https://ideone.com/XA44Y
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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