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

/**
 * @param {number} num
 * @return {boolean}
 */
var isUgly = function(num) {
    "use strict";
    if (num <= 0) {
        return false;
    }
    if (num === 1) {
        return true;
    }
    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;
};