005. Longest Palindromic Substring

#!/usr/bin/env python3

__author__ = 'Wei Mu'

class Solution:
    def Palindromehelper(self, s):
        if len(s) == 1 or len(set(s)) == 1:
            return True

        if len(s)%2 == 0:
            left  = int(len(s)/2 - 1)
            right = int(len(s)/2)
            for i in range(right):
                if s[left - i] != s[right + i]:
                    return(False)
            return(True)
        else:
            middle = len(s)//2
            for i in range(middle + 1):
                if s[middle - i] != s[middle + i]:
                    return(False)
            return(True)
        
    def longestPalindrome(self, s):
        """
        :type s: str
        :rtype: str
        """
        
        if len(s) < 2 or len(set(s)) == 1 or self.Palindromehelper(s) == True:
            return(s)
        
        cur_len = start = end = 0
                
        for i in range(len(s)):
            for j in range(min(i + 1, len(s) - i)):
                odd = self.Palindromehelper(s[i-j:i+j+1])
                even = self.Palindromehelper(s[i-j:i+j+2])
                
                if odd == False and even == False:
                    break
                
                if odd:
                    if 2 * j + 1 > cur_len:
                        cur_len = 2 * j + 1 
                        start = i - j
                        end = i + j + 1
                
                if i+j+1 < len(s) and even:
                    if  2 * j + 2 > cur_len:
                        cur_len = 2 * j + 2
                        start = i - j
                        end = i + j + 2

        return(s[start:end])