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Question

Formatted question description: https://leetcode.ca/all/263.html

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

Algorithm

Keep being devided by these prime numbers, if the remaining number is 1, it is an ugly number.

Code

• Java
• Python
• C++
• Go
• Javascript
• Php

• 
  public class Ugly_Number {
      class Solution {
          public boolean 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;
              }
              return num == 1;
          }
      }
  }
  
  ############
  
  class Solution {
      public boolean isUgly(int n) {
          if (n < 1) return false;
          while (n % 2 == 0) {
              n /= 2;
          }
          while (n % 3 == 0) {
              n /= 3;
          }
          while (n % 5 == 0) {
              n /= 5;
          }
          return n == 1;
      }
  }
  

• class Solution:
      def isUgly(self, n: int) -> bool:
          if n < 1:
              return False
          for x in [2, 3, 5]:
              while n % x == 0:
                  n //= x
          return n == 1
  
  ############
  
  class Solution(object):
    def isUgly(self, n):
      """
      :type num: int
      :rtype: bool
      """
      if n <= 0:
        return False
      while n % 2 == 0 or n % 3 == 0 or n % 5 == 0:
        if n % 2 == 0:
          n /= 2
        if n % 3 == 0:
          n /= 3
        if n % 5 == 0:
          n /= 5
      if n == 1:
        return True
      return False
  
  

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

• func isUgly(n int) bool {
  	if n < 1 {
  		return false
  	}
  	for _, x := range []int{2, 3, 5} {
  		for n%x == 0 {
  			n /= x
  		}
  	}
  	return n == 1
  }
  

• /**
   * @param {number} n
   * @return {boolean}
   */
  var isUgly = function (n) {
      if (n < 1) return false;
      while (n % 2 === 0) {
          n /= 2;
      }
      while (n % 3 === 0) {
          n /= 3;
      }
      while (n % 5 === 0) {
          n /= 5;
      }
      return n === 1;
  };
  
  

• class Solution {
      /**
       * @param Integer $n
       * @return Boolean
       */
      function isUgly($n) {
          while ($n) {
              if ($n % 2 == 0) $n = $n / 2;
              else if ($n % 3 == 0) $n = $n / 3;
              else if ($n % 5 == 0) $n = $n / 5;
              else break;
          }
          return $n == 1;
      }
  }
  

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