409. Longest Palindrome

https://leetcode.com/problems/longest-palindrome/

solution

class Solution:
    def longestPalindrome(self, s: str) -> int:
        ss = set()
        for letter in s:
            if letter not in ss:
                ss.add(letter)
            else:
                ss.remove(letter)
        if len(ss) != 0:
            return len(s) - len(ss) + 1
        else:
            return len(s)

时间复杂度：O() 空间复杂度：O()