longest_palindromic_substr.py (762B)
| # 5. Longest Palindromic Substring
"""
given a string 's', return the longest palindromic substring in 's'
"""
class Solution(object):
def helper(self, s, l, r):
while l >= 0 and r < len(s) and s[l] == s[r]:
l -= 1
r += 1
return s[l + 1 : r]
def longestPalindrome(self, s):
ans = ""
for i in range(len(s)):
tmp = self.helper(s, i, i)
if len(tmp) > len(ans):
ans = tmp
tmp = self.helper(s, i, i + 1)
if len(tmp) > len(ans):
ans = tmp
return ans
if __name__ == "__main__":
obj = Solution()
print(obj.longestPalindrome("babad")) # expect: bab
print(obj.longestPalindrome("cbbd")) # expect: bb
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