LeetCode: 263. Ugly Number

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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:

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

Example 2:

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

Example 3:

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

代码实现

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