263.ugly-number

Statement

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Metadata

Link: 丑数
Difficulty: Easy
Tag: 数学

丑数就是只包含质因数 2、3 和 5 的正整数。

给你一个整数 n ，请你判断 n 是否为丑数。如果是，返回 true ；否则，返回 false 。

示例 1：

输入：n = 6
输出：true
解释：6 = 2 × 3

示例 2：

输入：n = 1
输出：true
解释：1 没有质因数，因此它的全部质因数是 {2, 3, 5} 的空集。习惯上将其视作第一个丑数。

示例 3：

输入：n = 14
输出：false
解释：14 不是丑数，因为它包含了另外一个质因数 7 。

提示：

-2³¹ <= n <= 2³¹ - 1

Metadata

Link: Ugly Number
Difficulty: Easy
Tag: Math

An ugly number is a positive integer whose prime factors are limited to 2, 3, and 5.

Given an integer n, return true if n is an ugly number.

Example 1:

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

Example 2:

Input: n = 1
Output: true
Explanation: 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.

Example 3:

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

Constraints:

-2³¹ <= n <= 2³¹ - 1

Solution

Python 3

class Solution:
    def isUgly(self, x: int) -> bool:
        if x <= 0:
            return False

        def gao(x, y):
            while x % y == 0:
                x /= y
            return x

        x = gao(x, 2)
        x = gao(x, 3)
        x = gao(x, 5)

        return x == 1

最后更新: October 11, 2023