LeetCode刷题笔记--263. Ugly Number

263. Ugly Number

Easy

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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].

好吧，这是我最近今天最快AC的题。纪念一下，真的很简单。

class Solution {
public:
    bool 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;
        if(num!=1)return false;
        else return true;
    }
};