263. Ugly Number

Description

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.

Solution

简单的难以置信

class Solution {
    public boolean isUgly(int num) {
        if (num < 1) return false;
        
        while (num > 1) {
            if (num % 2 == 0) {
                num /= 2;
            } else if (num % 3 == 0) {
                num /= 3;
            } else if (num % 5 == 0) {
                num /= 5;
            } else {
                return false;
            }
        }
        
        return true;
    }
}