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[leetcode] problem 263 – ugly number

admin 11月 13, 2020 0

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

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public boolean (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;
}
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