263. Ugly Number

Write a program to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

判断一个数是不是只由2，3，5组成，1是一种特殊情况。思路是用这个数把2，3，5除干净，看剩下的数是不是1。代码如下：

public boolean isUgly(int num) {    if(num==1) return true;    if(num==0) return false;    while(num%2==0) num=num>>1;    while(num%3==0) num=num/3;    while(num%5==0) num=num/5;    return num==1;}