using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SoloLearn { class Program { static int MAX = 10000; static void Sieve(ref List l) { bool[] b = new bool[MAX / 2 + 100]; for(int i = 1; i <= (Math.Sqrt(MAX) - 1) / 2; i++) for (int j = (i * (i + 1)) << 1; j <= MAX / 2; j = j + 2 * i + 1) b[j] = true; l.Add(2); for(int i = 1; i <= MAX / 2; i++) if(b[i] == false) l.Add(2 * i + 1); } static void Goldbach(int n, List p) { Console.WriteLine("{0}:", n); Console.WriteLine(); for(int i = 0; p[i] <= n / 2; i++) { int d = n - p[i]; if(p.BinarySearch(d) >= 0) { Console.WriteLine("{0} + {1}", p[i], d); } } Console.WriteLine(); } static void Main(string[] args) { var primes = new List(); Sieve(ref primes); /****************** INPUT IS TWO NUMBERS SEPERATED BY A COMMA e. g. 4,8 IF YOU WANT IT TO ONLY DO ONE, INPUT IT TWICE e. g. 12,12 *******************/ string[] s = Console.ReadLine().Split(','); int n0 = int.Parse(s[0]); int n1 = int.Parse(s[1]); if(n0 <= 2 || n1 <= 2 || n1 < n0 || n0 % 2 != 0 || n1 % 2 != 0) { Console.WriteLine("both numbers must be even and bigger than two, and the second number must be bigger than or equal to the second one"); return; } for(int i = n0; i <= n1; i += 2) Goldbach(i, primes); } } }

goldbach conjecture