Insert Spaces to Highlight the Longest Palindromic Prefix/Suffix Match

Problem Given a string s. If s can be written as: s = L + M + reverse(L) where L can be empty, M is the remaining middle part, and reverse(L) is L reversed. Output the string by inserting single spaces between characters in L and reverse(L) (character-by-character), while keeping the middle part M unchanged. If adjacent parts exist, separate them by a single space. Example: Input: abcxyba L = "ab", M = "cxy", reverse(L) = "ba" Output: a b cxy b a If multiple decompositions are possible, choose the one with the longest L. I/O Input: a single string s Output: the transformed string Constraints 1 <= len(s) <= 2 * 10^5 s contains visible ASCII characters (no spaces) Expected complexity: O(n) or O(n log n) Examples s = "abcxyba" → "a b cxy b a" s = "abba" → "a b b a" (M is empty) s = "abcd" → "abcd" (L is empty) Example Input abcxyba Output a b cxy b a