3646: Next Special Palindrome Number

Problem Statement

You are given an integer n.

A number is called special if:

  • It is a palindrome.
  • Every digit k in the number appears exactly k times.

Return the smallest special number strictly greater than n.

Example 1:

Input: n = 2

Output: 22

Explanation:

22 is the smallest special number greater than 2, as it is a palindrome and the digit 2 appears exactly 2 times.

Example 2:

Input: n = 33

Output: 212

Explanation:

212 is the smallest special number greater than 33, as it is a palindrome and the digits 1 and 2 appear exactly 1 and 2 times respectively.

Constraints:

  • 0 <= n <= 1015

Code Solution