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: is not ugly since it includes another prime factor . 147
Note:
-
1
is typically treated as an ugly number. - Input is within the 32-bit signed integer range: [−231, 231 − 1].
编写一个程序判断给定的数是否为丑数。
丑数就是只包含质因数 2,5
的正整数。
示例 1:
输入: 6 输出: true 解释: 6 = 2 × 3
示例 2:
输入: 8 输出: true 解释: 8 = 2 × 2 × 2
示例 3:
输入: 14 输出: false 解释: 不是丑数,因为它包含了另外一个质因数 。147
说明:
-
1
是丑数。 - 输入不会超过 32 位有符号整数的范围: [−231, 231 − 1]。
20ms
1 class Solution { 2 func isUgly(_ num: Int) -> Bool { 3 if num < 1 {return false} 4 var number:Int = num 5 while (number % 2 == 0) 6 { 7 number /= 2 8 } 9 while (number % 3 == 0) 10 { 11 number /= 3 12 } 13 while (number % 5 == 0) 14 { 15 number /= 5 16 } 17 return number == 1 18 } 19 }
16ms
1 class Solution { 2 func maxDiv(_ num: inout Int,_ div: Int) { 3 while (num % div == 0) { 4 num = num/div 5 } 6 } 7 8 func isUgly(_ num: Int) -> Bool { 9 if(num == 0) { 10 return false 11 } 12 var no = num 13 maxDiv(&no,2) 14 maxDiv(&no,3) 15 maxDiv(&no,5) 16 17 if(no == 1){ 18 return true 19 } 20 else { 21 return false 22 } 23 24 } 25 }
20ms
1 class Solution { 2 func isUgly(_ num: Int) -> Bool { 3 guard num > 0 else {return false} 4 var n = num 5 6 let divs = [2,3,5] 7 for d in divs { 8 while n % d == 0 { 9 n /= d 10 } 11 } 12 return n == 1 13 } 14 }
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