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.

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

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判断一个数是否是丑数，算法不难，但是要注意对0的讨论要放在最前面

代码如下：

class Solution {
public:
    bool isUgly(int num) {
        if (num == 0)
            return false;
        while (num % 2 == 0)
            num /= 2;
        while (num % 3 == 0)
            num /= 3;
        while (num % 5 == 0)
            num /= 5;
        return num == 1;
    }
};