fork download
copy 
  1.  
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5. #include <math.h>
  6. #define MAX 20000001
  7. char prime[MAX];
  8.  
  9. void primeGenerator( long long int m )
  10. {
  11.  
  12.     long long int i,j,x;
  13.  
  14.     x = sqrt(m);
  15.  
  16.     prime[0] = prime[1] = 0;
  17.  
  18.     for( i = 4; i <= m; i += 2 )
  19.         prime[i] = 0;
  20.  
  21.     for( i = 3; i <= x; i += 2 )
  22.     {
  23.  
  24.         if(prime[i])
  25.             for( j = i * i; j <= m; j += i )
  26.                 prime[j] = 0;
  27.     }
  28.  
  29.     return ;
  30.  
  31. }
  32.  
  33. int FindPrime( long long int n, long long int m )
  34. {
  35.  
  36.      long long int i,res = 0;
  37.  
  38.     for( i = 2; i <= m/2; i++ )
  39.     {
  40.  
  41.         if( prime[i] && prime[i+2] )
  42.         {
  43.             res++;
  44.  
  45.             if( res == n )
  46.                 break;
  47.         }
  48.     }
  49.  
  50.     return i;
  51.  
  52. }
  53.  
  54. int main()
  55. {
  56.  
  57.  
  58.     long long int i,n,m = 20000000,ans;
  59.  
  60.     for( i = 0; i <= m; i++ )
  61.         prime[i] = 1;
  62.  
  63.     primeGenerator(m);
  64.  
  65.     while( scanf("%lld",&n) != EOF )
  66.  
  67.     {
  68.  
  69.         ans = FindPrime(n,m);
  70.  
  71.         if(ans)
  72.             printf("(%lld, %lld)\n",ans,ans+2);
  73.  
  74.         else
  75.             printf("Goldbach's conjecture is wrong.\n");
  76.  
  77.     }
  78.  
  79.     return 0;
  80. }
  81.  
Success #stdin #stdout 0.48s 21688KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Standard output is empty
https://ideone.com/gOH9Nw
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!