The greatest common divisor of two positive integers can be found with a very old trick: while the two numbers differ, replace the larger one by the difference between them. When they become equal, that value is the GCD. Write gcd_subtract(a, b) that implements this with a loop.
Examples
Input: a = 48, b = 18
Output: 6
Explanation: (48,18) -> (30,18) -> (12,18) -> (12,6) -> (6,6)
Input: a = 7, b = 7
Output: 7
Constraints
1 <= a, b <= 10**5
Goals
- Loop until two values become equal
- Change whichever variable is larger each step