/****************************************** Author: Nautash Ahmad Created: 25th July, 2018 ------------------------------------------- Description: Goldbach's conjecture is a rule in math that states the following: every even number greater than 2 can be expressed as the sum of two prime numbers. Write a program that finds every possible pair of prime numbers, whose sum equals the given number or a set of numbers within a range. For example: Input: 16 Output: 3 + 13 5 + 11 Input: 32 Output: 3 + 29 13 + 19 Input: 4, 8 Output: 4: 2 + 2 6: 3 + 3 8: 3 + 5 ------------------------------------------- Note: This program takes only one input and then calculate all possible combinations of prime numbers whom sum is equal to input. Number should be entered greater than or equal '4' so that output could be calculatd according to Goldbach's Conjecture rules. '1' is not considered as Prime Number in this program as per Goldbach's Conjecture rules. ******************************************/ #include #include using namespace std; void PrimeNumberCheck(int num, vector &myVec); int main() { int num1 = 0; vector myVec(0); cout << "Enter number: "; cin >> num1; if(num1 % 2 != 0 || num1 < 4) { cout << "\nEnter an even number or number Greater than \'4\'\n"; return 0; } else cout << "\nYou entered: " << num1 << endl; for(int i = 2; i < num1; i++) { PrimeNumberCheck(i, myVec); } for(int i = 0; i < myVec.size(); i++) { for(int j = i; j < myVec.size(); j++) { if((myVec[i]+myVec[j]) == num1) { cout << myVec.at(i) << " + " << myVec.at(j) << " = " << num1 << endl; } } } } void PrimeNumberCheck(int num, vector &myVec) { bool isPrime = true; for(int i = 2; i < num; i++) { if(num % i == 0) { isPrime = false; break; } } if(isPrime) myVec.push_back(num); }