【13_263】Ugly Number

简单题

Ugly Number

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Question

Total Accepted: 32635 Total Submissions: 94009 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.

Discuss中总有惊喜：

Java：

for (int i=2; i<6 && num>0; i++)
    while (num % i == 0)
        num /= i;
return num == 1;

Python：

for p in 2, 3, 5:
    while num % p == 0 < num:
        num /= p
return num == 1

C++：（其中&&之后的num怎么理解？）

for (int i=2; i<6 && num; i++)
    while (num % i == 0)
        num /= i;
return num == 1;

自己的：

C++：

class Solution {
public:
    bool isUgly(int num) {
        if (num <= 0)    
            return false;
        if (num == 1)
            return true;
            
        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;
    }
};