python-兩數求最大公因數
遞歸 (慢)
def gcd(a,b): if b == 0 : return a return gcd(b,a % b)
迭代 (快)
def gcd(a,b): while b != 0: a,b = b,a%b return a
excerpt from https://www.itdaan.com/tw/1dc772d8ca54126038e79c1f63cc889d