Goldbach's Conjecture | Algorithms

Goldbach's Conjecture | Algorithms

by SJ · February 21, 2015 Goldbach's con­jec­ture — Every even inte­ger greater than 2 can be rep­re­sented as the sum of two primes numbers. Exam­ple: Given Num­ber : 200 Prime Numbers are 3 197 Prime Numbers are 7 193 Prime Numbers are 19 181 Prime Numbers are 37 163 Prime Numbers are 43 157 Prime Numbers are 61 139 Prime Numbers are 73 127 Prime Numbers are 97 103 Approach: Check if num­ber is less than 2, return. Nav­i­gate i, from 3 to num­ber check if i and (x-i) is prime, if yes, Print it Code: public class GoldbachConjecture { public static void Goldbach(int x) { if (x % 2 != 0) { System.out.println("Not Even"); return; } if (x <= 2) { System.out.println("Less than 2"); return; } for (int i = 3; i < x / 2; i++) { if (isPrime(i) && isPrime(x - i)) { System.out.println("Prime Numbers are " + i + " " + (x - i)); } } } public static boolean isPrime(int x) { for (int i = 2; i < x / 2; i++) { if (x % i == 0) { return false; } } return true;

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