[LeetCode] Ugly Number

No matter what language you use on the OJ, you may refer to Stefan's post for a solution. The C++ is rewritten below, just really concise.

class Solution {
public:
    bool isUgly(int num) {
        for (int i = 2; i < 6 && num; i++)
            while (!(num % i)) num /= i;
        return num == 1;
    }
};

Note that i = 4 will simply be skipped after we try to divide by 2 as much as possible.