class Solution:
def longestPalindrome(self, s: str) -> str:
def checkPalindrome(l, r):
while l >=0 and r < len(s) and s[l] == s[r]:
l-=1
r+=1
return r - l - 1
longest = ""
for i in range(len(s)):
center = checkPalindrome(i, i)
acenter = checkPalindrome(i, i+1)
max_len = max(center, acenter)
if max_len > len(longest):
longest = s[i - (max_len - 1)// 2: i + max_len // 2 + 1]
return longest