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Shortest Palindrome

Problem Statement​

You are given a string s. You can convert s to a palindrome by adding characters in front of it.

Return the shortest palindrome you can find by performing this transformation.

Leetcode Link

Example 1:​

Input: s = "aacecaaa"
Output: "aaacecaaa"

Example 2:​

Input: s = "abcd"
Output: "dcbabcd"

Constraints:​

  • 0 <= s.length <= 5 * 104
  • s consists of lowercase English letters only.

Code​

Python Code

class Solution:
    def shortestPalindrome(self, s):
        r = s[::-1]
        for i in range(len(s) + 1):
            if s.startswith(r[i:]):
                return r[:i] + s