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].
LeetCode:链接
根据定义,依次将所给的数除以 2,3,5 直至无法除尽,如果这时得到1则说明所给的数的质因子不超出2,3,5三个数,否则说明有其他质因数。
class Solution(object):
def isUgly(self, num):
"""
:type num: int
:rtype: bool
"""
if num >= 2147483647 or num <= 0:
return False
for i in [2,3,5]:
while num % i == 0:
num = num // i
if num == 1:
return True
return False