Longest Palindromic Substring in Mathematica

Published on 28 April 2022 (Updated: 02 February 2023)

Longest Palindromic Substring in Mathematica

Welcome to the Longest Palindromic Substring in Mathematica page! Here, you’ll find the source code for this program as well as a description of how the program works.

Current Solution

(* Code *)

(* Brute force approach of generating all substrings and testing: *)

longestPalindromicSubstring = word \[Function] First @ MaximalBy[
     Select[PalindromeQ][
      Flatten[Table[
        StringTake[word, {i, j}],
        {i, 1, StringLength[word]}, {j, i + 1, StringLength[word]}],
       1]],
     StringLength,
     UpTo[1]];

(* The outer function provides the 'user interface' (e.g., the string parsing): *)

longestPalindromicSubstringMain = Function[{s},
   Module[{e = "Usage: please provide a string that contains at least one palindrome"},
    Catch[
     longestPalindromicSubstring @
      If[StringLength[s] > 0, s, Throw[e]]]]];


(* Valid Tests *)

Print /@ longestPalindromicSubstringMain /@ {
    "racecar",
    "kayak mom",
    "step on no pets"
    };


(* Invalid Tests *)

longestPalindromicSubstringMain[""]

Longest Palindromic Substring in Mathematica was written by:

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How to Implement the Solution

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How to Run the Solution

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