Challenge 1: Find the greatest common divisor

In this lesson, the user will find the greatest common divisor (GCD) using recursion.

What is GCD?

The GCD of two integers is the largest integer that can fully divide both numbers, without a remainder.

How to find GCD?

What is the greatest common divisor of 54 and 36?

The number 3636 can be expressed as a product of two integers in several different ways:

$ 36\times 1=18\times 2= 12\times 3 = 9\times 4$

Thus the divisors for 3636 are 1,2,3,4,6,9,12,18,361, 2, 3, 4, 6, 9, 12, 18, 36

The number 5454 can be expressed as a product of two integers in several different ways:

$ 54\times 1=27\times 2= 18\times 3=9\times 6 $

Thus the divisors for 5454 are 1,2,3,6,9,18,271, 2, 3, 6, 9, 18, 27

Common divisors are 1,2,3,6,91, 2, 3, 6, 9 and 1818.

Greatest common divisor or GCD for 3636 and 5454 is 1818.

Problem Statement

Write a recursive function that computes the GCD of two integers.

Instructions

  1. The function should take two integers, whose GCD is to be computed, as input.
  2. The function should return the GCD of the two integers as output.
  3. The function should be recursive.

Sample Input: 24, 18

Sample Output: 6

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