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Grokking the Coding Interview Patterns in C#

Solution: Next Palindrome Using Same Digits

Explore how to determine the smallest palindrome larger than a given numeric palindrome by rearranging digits. Understand and apply the two pointer technique to manipulate the left half of the string efficiently, then mirror it to form the new palindrome. This lesson helps you solve palindrome rearrangement problems with optimal time and space complexity.

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Statement

Given a numeric string, numStr, 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 numStr 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:

  • 1≤1 \leq ...