Search⌘ K
AI Features

Solution: Next Palindrome Using Same Digits

Discover how to use the two-pointer method to find the next palindrome larger than a given numeric palindrome by rearranging digits. Learn to split the number, identify the next lexicographical permutation of the left half, and mirror it to form the result efficiently.

Statement

Given a numeric string, num_str, representing a palindromeA palindrome is a number that reads the same backward as it does forward. (composed only of digits). Return the smallest palindrome larger than num_str that can be created by rearranging its digits. If no such palindrome exists, return an empty string "".

Consider the following example to understand the expected output for a given numeric string:

  • input string = "123321"

  • The valid palindromes made from the exact digits are "213312", "231132", "312213", "132231", "321123".

  • We return the palindrome "132231" because it is the smallest palindrome larger than the input string "123321".

Constraints:

  • 11 \leq ...