# 263. Ugly Number 丑数

@TOC

[LeetCode]

Total Accepted: 22335 Total Submissions: 67449 Difficulty: Easy

## # 题目描述

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`.

Example 1:

``````Input: 6
Output: true
Explanation: 6 = 2 × 3
``````

Example 2:

``````Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2
``````

Example 3:

``````Input: 14
Output: false
Explanation: 14 is not ugly since it includes another prime factor 7.
``````

Note:

1. 1 is typically treated as an ugly number.
2. Input is within the 32-bit signed integer range: [−231, 231 − 1].

## # 解题方法

### # 除去2,3,5因子

python解法。

``````class Solution(object):
def isUgly(self, num):
"""
:type num: int
:rtype: bool
"""
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
``````

Java解法：

``````public static boolean isUgly(int num) {
if (num == 1) {
return true;
}

while (num >= 2 && num % 2 == 0) {
num = num / 2;
}
while (num >= 3 && num % 3 == 0) {
num = num / 3;
}
while (num >= 5 && num % 5 == 0) {
num = num / 5;
}
return num == 1;
}
``````

``````public class Solution {
public boolean isUgly(int num) {
int[] divides ={2,3,5};
for(int i = 0; i < divides.length && num > 0; i++){
while(num % divides[i] == 0){
num /= divides[i];
}
}
return num == 1;
}
}
``````

## # 日期

2015/10/16 21:20:23 2018 年 11 月 21 日 —— 又是一个美好的开始