#214

Shortest Palindrome

hard · verified · 42% accepted · 4,551 likes · top 23%

string · rolling hash · string matching · hash function

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Description

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.

Example 1:

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

Example 2:

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

Solution