leetcode:263 Ugly Number－每日编程第十七题

Ugly Number

Total Accepted: 31482 Total Submissions: 90982 Difficulty: Easy

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：

1).＝＝优先级高于&，因此要记得加括号。

 1 class Solution {
 2 public:
 3     bool isUgly(int num) {
 4         if(num==0){
 5             return false;
 6         }
 7         while((num&1)==0){
 8             num>>=1;
 9         }
10         while(num%3==0){
11             num/=3;
12         }
13         while(num%5==0){
14             num/=5;
15         }
16         if(num==1){
17             return true;
18         }else{
19             return false;
20         }
21     }
22 };