Longest Palindrome by Concatenating Two Letter Words LeetCode solution in Python

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class Solution(object):
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    def longestPalindrome(self, words):
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        wc = collections.Counter(words)
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        aa = 0  # count how many words contain only two identical letters like 'aa'
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        center = 0  # if one count of 'aa' is odd, that means it can be the center of the palindrome, answer can plus 2
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        abba = 0  # count how many word pairs like ('ab', 'ba') and they can put on both sides respectively
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        for w, c in wc.items():
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            if w[0] == w[1]:  # like 'aa', 'bb', ...
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                aa += (
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                    c // 2 * 2
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                )  # if there are 3 'aa', we can only use 2 'aa' put on both sides respectively
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                # if one count of 'aa' is odd, that means it can be the center of the palindrome, answer can plus 2
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                if c % 2 == 1:
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                    center = 2
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            else:
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                abba += min(wc[w], wc[w[::-1]]) * 0.5  # will definitely double counting
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        return aa * 2 + int(abba) * 4 + center