package Maths;

/**
 * @author https://github.com/shellhub/
 */
public class GCDRecursion {
 public static void main(String[] args) {
 System.out.println(gcd(20, 15)); /* output: 5 */
 System.out.println(gcd(10, 8)); /* output: 2 */
 System.out.println(gcd(gcd(10, 5), gcd(5, 10))); /* output: 5 */
 }

 /**
 * get greatest common divisor
 *
 * @param a the first number
 * @param b the second number
 * @return gcd
 */
 public static int gcd(int a, int b) {

 if (a < 0 || b < 0) {
 throw new ArithmeticException();
 }

 if (a == 0 || b == 0) {
 return Math.abs(a - b);
 }

 if (a % b == 0) {
 return b;
 } else {
 return gcd(b, a % b);
 }
 }
}