LeetCode 263.Ugly Number

摘要: 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.
思路：判断一个数是否为“ugly number”，只需要判断该数能否有限次的被2，3，5整除，且1也为“ugly number”，即最后只要最后的结果为1即为“ugly number”。
language-javascript

/**
* @param {number} num
* @return {boolean}
*/
var isUgly = function(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)? true : false;
};