Watch 10 video solutions for Find the Count of Good Integers, a hard level problem involving Hash Table, Math, Combinatorics. This walkthrough by NeetCode has 111,386 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
You are given two positive integers n and k.
An integer x is called k-palindromic if:
x is a palindrome.x 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 <= 9