35 lines
1.1 KiB
C++
35 lines
1.1 KiB
C++
// Source : https://leetcode.com/problems/ugly-number/
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// Author : Hao Chen
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// Date : 2015-10-21
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/***************************************************************************************
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*
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* Write a program to check whether a given number is an ugly number.
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*
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* Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For
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* example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.
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*
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* Note that 1 is typically treated as an ugly number.
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*
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* Credits:Special thanks to @jianchao.li.fighter for adding this problem and creating
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* all test cases.
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*
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***************************************************************************************/
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class Solution {
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public:
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//greeting algorithm
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bool isUgly(int num) {
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if ( num == 0 ) return false;
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if ( num == 1 ) return true;
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//becasue the 2,3,5 are prime numbers, so, we just simply remove each factors
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//by keeping dividing them one by one
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while ( num % 2 == 0 ) num /= 2;
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while ( num % 3 == 0 ) num /= 3;
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while ( num % 5 == 0 ) num /= 5;
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return num == 1;
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}
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};
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