19
08/2015
[LeetCode] Ugly Number
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
. 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.
解题思路:
题意为只有2、3、5三个因子的数成为Ugly Number。1也认为是Ugly Number。因此我们只需要不断的除以2/3/5即可(倘若能够整除)
class Solution { public: bool 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; } };
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