LeetCode263 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.

编写一个程序来检查给定的数字是否是一个丑数。丑数是正数并且它的质因数只有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

思路

 

class Solution {
    public boolean isUgly(int num) {
        if(num == 0) return false;
        int[] primes = {2, 3, 5};
        for(int i : primes)
            while(num % i == 0) num /= i;
        return num == 1;
    }
}