Chapter 5, Problem 30CRP

Design a recursive version of the Euclidean algorithm (Question 3 of Section 5.2).

Question 3 of Section 5.2:

3 The Euclidean algorithm finds the greatest common divisor of two positive integers X and Y by the following process:

As long as the value of neither X nor Y is zero, assign the larger the remainder of dividing the larger by the smaller. The greatest common divisor, if it exists, will be the remaining non-zero value.