Official algorithmic problem description and constraints.
You are given two positive integers n and k.
An integer x is called k-palindromic if:
x is a palindromex is divisible by k.An integer is called good if its digits can be rearranged to form a k-palindromic integer. For example, for k = 2, 2020 can be rearranged to form the k-palindromic integer 2002, whereas 1010 cannot be rearranged to form a k-palindromic integer.
Return the count of good integers containing n digits.
Note that any integer must not have leading zeros, neither before nor after rearrangement. For example, 1010 cannot be rearranged to form 101.
Example 1:
Input: n = 3, k = 5
Output: 27
Explanation:
Some of the good integers are:
Example 2:
Input: n = 1, k = 4
Output: 2
Explanation:
The two good integers are 4 and 8.
Example 3:
Input: n = 5, k = 6
Output: 2468
Constraints:
1 <= n <= 101 <= k <= 9Detailed video explanations, mathematical intuition, and clean C++ implementation code.