Problem
Return the greatest common divisor of a and b. Euclid's algorithm repeatedly replaces (a, b) with (b, a mod b) until b is 0.
Implement gcd(a, b).
Input
a: The first number. b: The second number.
Output
Return gcd(a, b). gcd(0, 0) is 0.
Constraints
0 ≤ a, b ≤ 10¹⁸
Examples
Example 1
Input:
a = 48
b = 18
Expected output:
expected = 6Input:
long long a = 48;
long long b = 18;
Expected output:
long long expected = 6;Input:
long a = 48;
long b = 18;
Expected output:
long expected = 6;Explanation
48 mod 18 = 12, 18 mod 12 = 6, 12 mod 6 = 0, so the answer is 6.
Example 2
Input:
a = 17
b = 5
Expected output:
expected = 1Input:
long long a = 17;
long long b = 5;
Expected output:
long long expected = 1;Input:
long a = 17;
long b = 5;
Expected output:
long expected = 1;Explanation
17 and 5 share no factor other than 1.
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.