LeetCode-214、最短回文串-困难

给定一个字符串 s，你可以通过在字符串前面添加字符将其转换为回文串。找到并返回可以用这种方式转换的最短回文串。

示例 1:

输入: "aacecaaa"
输出: "aaacecaaa"

示例 2:

输入: "abcd"
输出: "dcbabcd"

 

代码：暴力法

class Solution:
    def shortestPalindrome(self, s: str) -> str:
        if len(s) <= 1:
            return s
        if s[::-1] == s:
            return s
        start = 0
        end = 0
        ind = 1
        while ind < len(s):
            piece = s[start:ind]
            if piece[::-1] == piece:
                end = ind
            ind += 1
        s1 = s[end:]
        ss = s1[::-1] + s
        return ss

递归法和KMP法参考：最短回文串