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Solution: Next Palindrome Using Same Digits

Explore how to find the next smallest palindrome larger than a given palindrome string by rearranging its digits. Learn to apply the two-pointer approach to efficiently generate the next lexicographical permutation of half the palindrome and mirror it, understanding step-by-step techniques to solve this problem with linear time complexity.

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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:

  • ...