45. buildPalindrome

Task

Given a string, find the shortest possible string which can be achieved by adding characters to the end of initial string to make it a palindrome.

Example

For st = "abcdc", the output should be
buildPalindrome(st) = "abcdcba".

Input/Output

• [execution time limit]
  4 seconds (py3)

• [input] string st
  A string consisting of lowercase English letters.
  Guaranteed constraints: 3 ≤ st.length ≤ 10.

• [output] string

My Solution

def buildPalindrome(st):
    maxIndex = -1
    for i in range(2, len(st) + 1):
        if st[-i:] == st[:-i - 1:-1]:
            maxIndex = -i
    return st + st[:maxIndex][::-1]