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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long int
  4. #define ull unsigned long long
  5. #define MAXNODES 200009
  6. #define mod 1073741824
  7. #define MAXTREE (MAXNODES << 2)
  8.  
  9. void kk ()
  10. {
  11.     ios::sync_with_stdio(0);
  12.     ios_base::sync_with_stdio(0);
  13.     cin.tie(0), cout.tie(0);
  14. }
  15.  
  16.  
  17. bool primes[1000005];
  18. vector<ll>v;
  19. void Sieve()
  20. {
  21.     for (int i=0;i<=1e6;i++)
  22.         primes[i]=1;
  23.     primes[0]=0;
  24.     primes[1]=0;
  25.     for (ll i=2;i<=1e6;i++)
  26.     {
  27.         if (primes[i])
  28.         {
  29.             v.push_back(i);
  30.             for (ll j=i*i;j<=1e6;j+=i)
  31.                 primes[j]=0;
  32.         }
  33.     }
  34. }
  35. int main()
  36. {
  37.  
  38.     kk ();
  39.  
  40.     /*  freopen("input.txt","r",stdin);
  41.       freopen("output.txt","w",stdout);*/
  42.  
  43.     Sieve();
  44.     int n;
  45.     while (cin>>n)
  46.     {
  47.         if (n==0)
  48.             break;
  49.         int mx=0;
  50.         ll a=-1,b=-1;
  51.         for (int i=0;i<v.size();i++)
  52.         {
  53.             ll temp=n-v[i];
  54.             if (temp>=0 && primes[temp])
  55.             {
  56.                 if (abs(temp-n)>=mx)
  57.                 {
  58.                     mx=abs(temp-n);
  59.                     a=min(v[i],temp);
  60.                     b=max(v[i],temp);
  61.                 }
  62.             }
  63.             else if (temp<0)
  64.                 break;
  65.         }
  66.         if (a==-1)
  67.             cout << "Goldbach's conjecture is wrong." << endl;
  68.         else
  69.         {
  70.  
  71.             cout << n << " = " << a << " + " << b << endl;
  72.         }
  73.     }
  74.     return 0;
  75. }
  76.  
Success #stdin #stdout 0s 16336KB
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https://ideone.com/dpJ16X
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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