LeetCode 263. Ugly Number（丑数字）

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本文介绍了一种检查给定数字是否为丑数的有效算法。丑数定义为仅包含质因数2、3和5的正整数。文章提供了一个简洁的Java代码示例，通过不断除以2、3和5来判断输入的数字是否符合丑数的定义。

原题网址：https://leetcode.com/problems/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.

思路：因式分解。

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