You are given a numeric string num, representing a very large palindrome.
Return the smallest palindrome larger than num that can be created by rearranging its digits. If no such palindrome exists, return an empty string "".
A palindrome is a number that reads the same backward as forward.
Example 1:
Input: num = "1221" Output: "2112" Explanation: The next palindrome larger than "1221" is "2112".
Example 2:
Input: num = "32123" Output: "" Explanation: No palindromes larger than "32123" can be made by rearranging the digits.
Example 3:
Input: num = "45544554" Output: "54455445" Explanation: The next palindrome larger than "45544554" is "54455445".
Constraints:
1 <= num.length <= 105numis a palindrome.