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// Source : https://leetcode.com/problems/ugly-number/

// Author : Hao Chen

// Date : 2015-10-21

/***************************************************************************************

* 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. For

* example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

* Note that 1 is typically treated as an ugly number.

* Credits:Special thanks to @jianchao.li.fighter for adding this problem and creating

* all test cases.

***************************************************************************************/

class Solution {

public:

//greeting algorithm

bool isUgly(int num) {

if ( num == 0 ) return false;

if ( num == 1 ) return true;

//becasue the 2,3,5 are prime numbers, so, we just simply remove each factors

//by keeping dividing them one by one

while ( num % 2 == 0 ) num /= 2;

while ( num % 3 == 0 ) num /= 3;

while ( num % 5 == 0 ) num /= 5;

return num == 1;

}

};