Given an integer num, return the number of digits in num that divide num.
An integer val divides nums if nums % val == 0.
Example 1:
Input: num = 7 Output: 1 Explanation: 7 divides itself, hence the answer is 1.
Example 2:
Input: num = 121 Output: 2 Explanation: 121 is divisible by 1, but not 2. Since 1 occurs twice as a digit, we return 2.
Example 3:
Input: num = 1248 Output: 4 Explanation: 1248 is divisible by all of its digits, hence the answer is 4.
Constraints:
1 <= num <= 109num does not contain 0 as one of its digits.