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Grokking the Coding Interview Patterns in Go

Solution: Next Palindrome Using Same Digits

Explore how to find the next smallest palindrome larger than a given numeric string by rearranging its digits. Learn to apply the two pointers technique to rearrange the left half of the palindrome and mirror it for efficient computation. Understand the step-by-step method to swap digits and reverse subsequences to achieve the next lexicographically larger palindrome or determine when no such palindrome exists.

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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:

  • ...