fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define ll long long
  4. // #define int long long int
  5. #define ld long double
  6. #define all(x) x.begin(), x.end()
  7. #define sortall(x) sort(all(x))
  8. #define endl '\n'
  9. #define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  10. template<class T>
  11. void printC (T Collection)
  12. {
  13.     for (auto&i:Collection)
  14.         cout << i << " \n";
  15.     cout << '\n';
  16. }
  17.  
  18. /*
  19.  * Think twice, code once
  20.  * Think of different approaches to tackle a problem: write them down.
  21.  * Think of different views of the problem. don't look from only one side.
  22.  * don't get stuck in one approach.
  23.  * common mistakes: - over_flow
  24.  *                  - out_of_bound index
  25.  *                  - infinite loop
  26.  *                  - corner cases
  27.  *                  - duplication counting.
  28. */
  29.  
  30. vector<bool> sieve()
  31. {
  32.     vector<bool> isPrime(1e6+1, true);
  33.     isPrime[0] = isPrime[1] = false;
  34.     for (int i = 2; i * i <= 1e6; ++i)
  35.         if (isPrime[i])
  36.             for (int j = i * i; j <= 1e6; j += i)
  37.                 isPrime[j] = false;
  38.     return isPrime;
  39. }
  40.  
  41. void solve()
  42. {
  43.     vector<bool> isPrime(sieve());
  44.     int q;
  45.     while (cin >> q && q != 0)
  46.     {
  47.         bool flag = true;
  48.         for (int i = 3; i < isPrime.size(); i += 2)
  49.         {
  50.             if (isPrime[i] && isPrime[q-i])
  51.             {
  52.                 cout << q << " = " << i << " + " << q-i << '\n';
  53.                 flag = false;
  54.                 break;
  55.             }
  56.         }
  57.         if (flag)
  58.             cout << "Goldbach's conjecture is wrong.\n";
  59.     }
  60. }
  61.  
  62. int main()
  63. {
  64. #ifndef ONLINE_JUDGE
  65.     freopen("input.txt", "r", stdin);
  66.     freopen("output.txt", "w", stdout);
  67.     freopen("Errors.txt", "w", stderr);
  68. #endif
  69.     fast
  70.     int t = 1;
  71.     // cin >> t;
  72.     while (t--)
  73.     {
  74.         solve();
  75.         if (t) cout << '\n';
  76.     }
  77.     cout << '\n';
  78.     return 0;
  79. }
Success #stdin #stdout 0.01s 5284KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 

	

		
	 
	
	
			

					
			
			
			
			
			
			
			
			

			
			
			
		

	
		
		

			

			                        







			
			

				

	
					
					 https://ideone.com/Z37eCh
					
					
					
					
					

												

												
						
						

					

					
					
					

						
language:

						
C++14 (gcc 8.3)

					

					

						
created:
								
						
6 days 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!