1.題目

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.

2.算法

從百科百科中我們知道，如果一個數丑陋，當這個數不為1的時候，對2，3，5相除就會最終為0

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