263. Ugly Number
https://github.com/openset/leetcode/tree/master/problems/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:14is not ugly since it includes another pime factor7.
Note:
1is typically treated as an ugly number.- Input is within the 32-bit signed integer range: [−231, 231 − 1]
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Time - log 2 N + log 3 N + log 5 N
Space - O(1)
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| public class Solution { | |
| /** | |
| * @param num: An integer | |
| * @return: true if num is an ugly number or false | |
| */ | |
| public boolean isUgly(int num) { | |
| int[] factors = new int[] {2, 3, 5}; | |
| for (int factor: factors) { | |
| while (num % factor == 0) { | |
| num /= factor; | |
| } | |
| } | |
| return num == 1; | |
| } | |
| } |
