写个最长回文子串吧~

def longest_palindrome(s):
    if not s:
        return ""
    def check_palindrome(t):
        for i in range(0, len(t) // 2 + len(t) % 2):
            if t[i] != t[-1 * i - 1]:
                return False
        return True

    value = [1 for i in range(len(s))]
    for i in range(1, len(s)):
        min_ = max(i - value[i - 1] - 1, 0)
        for j in range(min_, i + 1):
            if s[j] == s[i]:
                if check_palindrome(s[j + 1: i]):
                    value[i] = i + 1 - j
                    break
    # print(value)
    max_value = value[0]
    ind = 0
    for k in range(len(value)):
        if value[k] > max_value:
            max_value = value[k]
            ind = k
    return s[ind + 1 - max_value:ind + 1]

# 测试通过
s_list =["", "a", "aa", "aba", "abcba", "abcdefeg"]
for s in s_list:
    print(longest_palindrome(s))

动态规划思维

动态规划、中心扩散、Manacher 算法