Canonical Palindrome — Solution & Editorial
At most one character may have an odd count. Build the sorted half from ⌊count/2⌋ of each letter, place the odd letter (single copy) in the middle, mirror the half.
Complexity: O(|S| + 26)
At most one character may have an odd count. Build the sorted half from ⌊count/2⌋ of each letter, place the odd letter (single copy) in the middle, mirror the half.
Complexity: O(|S| + 26)