在Python中保存最长列表

Question

def longestPalindrome(s):
    longest = []
    palindrome = []
    for i in range(len(s)):
        for j in range(i, len(s)):
            palindrome.append(s[j])
            if palindrome == palindrome[::-1]:
                print(palindrome)
                longest = palindrome
        palindrome = []
    return longest

print(longestPalindrome("What kind of racecar do you drive?"))

我尝试通过像这样更改if语句来只获得最长的回文。

if palindrome == palindrome[::-1] and len(palindrome) > len(longest):

这并不像预期的那样有效。我只打印第一个回文[“w”]，然后在列表中返回整个字符串[“w”,“h”,...]

Answer 1

当执行lengte=palindrome时，您将lengte列表的引用指向palindrome，因此palindrome.append(S[j])也会追加到lengte

你需要复印名单。

longest = palindrome[:]

例如，

def longestPalindrome(s):
    longest = []
    palindrome = []
    for i in range(len(s)):
        for j in range(i, len(s)):
            palindrome.append(s[j])
            if palindrome == palindrome[::-1] and len(palindrome) > len(longest):
                # print(palindrome, i, j)
                longest = palindrome[:]
        palindrome = []
    return ''.join(longest)

print(repr(longestPalindrome("What kind of racecar do you drive?")))