leetCode#5. Longest Palindromic Substring

Description

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.

Example:

Input: "babad"

Output: "bab"

Note: “aba” is also a valid answer.
Example:

Input: "cbbd"

Output: "bb"

Code

class Solution(object):
    def longestPalindrome(self, s):
        """
        :type s: str
        :rtype: str
        """
        start, end = 0, 0
        for idx in range(len(s)):
            len1 = self.cntLen(s, idx, idx + 1)
            len2 = self.cntLen(s, idx, idx)
            l = max(len1, len2)
            if l > start - end:
                start = idx - (l - 1) / 2
                end = idx + l / 2
        return s[start:end + 1]

    def cntLen(self, s, l, r):
        while l >= 0 and r < len(s) and s[l] == s[r]:
            l -= 1
            r += 1
        return r - l - 1

Conclusion

这道题没有想到方法，是照着solution写的，还有别的方法可以学习。该题教程