LeetCode | 0409. Longest Palindrome最长回文串Python

Posted 2021-03-04 Wonz

LeetCode 0409. Longest Palindrome最长回文串【Easy】【Python】【字符串】

Problem

LeetCode

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters.

This is case sensitive, for example "Aa" is not considered a palindrome here.

Note:
Assume the length of given string will not exceed 1,010.

Example:

Input:
"abccccdd"

Output:
7

Explanation:
One longest palindrome that can be built is "dccaccd", whose length is 7.

问题

力扣

给定一个包含大写字母和小写字母的字符串，找到通过这些字母构造成的最长的回文串。

在构造过程中，请注意区分大小写。比如 "Aa" 不能当做一个回文字符串。

注意:
假设字符串的长度不会超过 1010。

示例 1:

输入:
"abccccdd"

输出:
7

解释:
我们可以构造的最长的回文串是"dccaccd", 它的长度是 7。

思路

字符串

统计字符串中各个字符个数。
最后尽可能多地输出偶数个相同字符。

Python3代码

class Solution:
    def longestPalindrome(self, s: str) -> int:
        import collections
        # 统计各字符个数
        count = collections.Counter(s).values()
        sum = 0
        for x in count:
            if x // 2 > 0:
                # 取偶数个字符
                sum += x // 2 * 2
        if sum == len(s):
            return sum
        else:
            return sum + 1

代码地址

GitHub链接