Java [Leetcode 263]Ugly Number
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
. 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.
解题思路:
根据丑数的定义,可以通过如下方法判断一个数字n是否为丑数:可以试着用2、3、5不断整除n,当n不能再被2、3、5整除时,判断n是否等于1,等于1则指定的数字是丑数(返回真),否则不是(返回假)。
代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 | public class Solution { 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 ; } } |
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