1842. Next Palindrome Using Same Digits

https://leetcode.com/problems/next-palindrome-using-same-digits

Description

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 <= 105

• num is a palindrome.

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