[LeetCode] Problem 263 - Ugly Number

Posted on | In ,

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.

Note

1 is typically treated as an ugly number.

Input is within the 32-bit signed integer range: [−2^31, 2^31 − 1].

Example

No.1

Input: 6

Output: true

Explanation: 6 = 2 × 3

No.2

Input: 8

Output: true

Explanation: 8 = 2 × 2 × 2

No.3

Input: 14

Output: false

Explanation: 14 is not ugly since it includes another prime factor 7.

Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
public boolean isUgly(int num) {
    if (num <= 0)
        return false;
    
    if (num == 1)
        return true;

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

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

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

    return num == 1;
}