辗转相除法（求最大公倍数）

一般写法：

public class Main {public static void main(String[] args) {System.out.println(gcd(18, 2));}private static int gcd(int a, int b) {// TODO Auto-generated method stubwhile (b != 0) {int c = a % b;a = b;b = c;}return a;}
}

递归实现

public class Main {public static void main(String[] args) {System.out.println(gcd(18, 2));}private static int gcd(int a, int b) {// TODO Auto-generated method stubif (b == 0) {return a;}return gcd(b, a%b);}
}