challenge-11

Challenge #11: 📖 The Studious Elves

In Santa's workshop, the elves are known for their love of puzzles and brain teasers. This year, they've come up with a special challenge: to create a Christmas palindrome.

A palindrome is a word that reads the same forwards and backward. The task is to determine if it's possible to transform a given string into a palindrome with, at most, a single exchange of letters.

/**
 * Determines if it's possible to form a palindrome with at most one letter exchange.
 * @param {string} word - The input string.
 * @returns {(number[]|null)} - Returns an array of two indices if a palindrome can be formed with one change,
 * an empty array if the input is already a palindrome, or null if it's not possible.
 */
function getIndexsForPalindrome(word) {
  // Implementation goes here
}

Examples

getIndexsForPalindrome('anna');      // Returns: []
getIndexsForPalindrome('abab');      // Returns: [0, 1]
getIndexsForPalindrome('abac');      // Returns: null
getIndexsForPalindrome('aaaaaaaa');  // Returns: []
getIndexsForPalindrome('aaababa');   // Returns: [1, 3]
getIndexsForPalindrome('caababa');   // Returns: null

Explanation

• If the input string is already a palindrome, the function returns an empty array.
• If it's not possible to form a palindrome, the function returns null.
• If a palindrome can be formed with one change, the function returns an array with the two positions (indexes) that must be swapped to create it.

Note:

• The function should always return the first valid pair of indices if multiple swaps are possible.
• Ensure the provided examples match the expected output.
• Feel free to add more examples or edge cases to thoroughly test the function.