Leetcode 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.

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最直接的办法就是不停的除以这些质数，如果剩余的数字是1的话就是Ugly number了

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Java code:

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

Reference:

http://www.cnblogs.com/grandyang/p/4741934.html