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Question

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

 263	Ugly Number

 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 is typically treated as an ugly number.
 Input is within the 32-bit signed integer range: [−231,  231 − 1].

 @tag-heap

Algorithm

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

Code

  • 
    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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