409. Longest Palindrome
from collections import Counter
class Solution:
def longestPalindrome(self, s):
"""
:type s: str
:rtype: int
"""
counter = Counter(s)
r = 0
for c in counter:
r += counter[c] // 2 * 2
if r % 2 == 0 and counter[c] % 2 == 1:
r += 1
return r