Leetcode 5最长回文子串(python)

def longestPalindrome(s):
    n = len(s)
    dp = [[False] * n for _ in range(n)]
    start = 0
    max_len = 1

    # 初始化对角线和相邻两个字符的情况
    for i in range(n):
        dp[i][i] = True
        if i < n - 1 and s[i] == s[i + 1]:
            dp[i][i + 1] = True
            start = i
            max_len = 2

    # 遍历字符串，逐渐增加子串的长度
    for length in range(3, n + 1):
        for i in range(n - length + 1):
            j = i + length - 1
            if s[i] == s[j] and dp[i + 1][j - 1]:
                dp[i][j] = True
                start = i
                max_len = length

    return s[start:start + max_len]