Initialize a dictionary (or array if considering the fixed alphabet) to count the occurrences of each letter in the string.
Iterate through the string, incrementing the count for each letter.
Initialize a variable length to 0, which will store the length of the longest palindrome.
Iterate through the counts of each letter.
a. Add the largest even number less than or equal to the count to length (this is done by adding count // 2 * 2).
b. If the count is odd and length is even, add 1 to length to account for a possible center.
Return the value of length.
Sorting and Pairing Approach for Longest Palindrome