Minimum Length of String After Operations — Python

# Time:  O(n + 26)
# Space: O(26)

# freq table
class Solution(object):
    def minimumLength(self, s):
        """
        :type s: str
        :rtype: int
        """
        cnt = [0]*26
        for x in s:
            cnt[ord(x)-ord('a')] += 1
        return sum(2-x%2 for x in cnt if x)


# Time:  O(n)
# Space: O(26)
import collections


# freq table
class Solution2(object):
    def minimumLength(self, s):
        """
        :type s: str
        :rtype: int
        """
        return sum(2-x%2 for x in collections.Counter(s).itervalues())