Ugly Number

lc 263 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. 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.

时间 O(logN) 空间 O(1)

public class Solution {
    public boolean isUgly(int num) {
        if(num == 0) return false;
        if(num == 1) return true;

        while( num % 2 == 0){
            num = num / 2;
        }
        while(num % 3 == 0){
            num = num / 3;
        }
        while(num % 5 == 0){
            num = num / 5;
        }
        return num == 1;
    }
}