leetcode 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.

这道题很简单嘛。

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

大神的方法也跟我差不多。先把一个除数除尽了，再除以另外一个除数。

public class Solution {    public static boolean isUgly(int num) {        if (num <= 0) {            return false;        }                int[] divisors = {2, 3, 5};                for(int d : divisors) {            while (num % d == 0) {                num /= d;            }        }        return num == 1;    }}