Find the Longest Substring Containing Vowels in Even Counts LeetCode solution in Python

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class Solution:
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    def findTheLongestSubstring(self, s: str) -> int:
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        integrals = [
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            (False, False, False, False, False)
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        ]  # integrals[10][mapping["a"]] == False means we have seen "a" appears even times before index 10
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        mapping = {"a": 0, "i": 1, "u": 2, "e": 3, "o": 4}
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        for v in s:
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            vector = list(integrals[-1])
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            if v in mapping:  # if v is a vowel
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                vector[mapping[v]] = not vector[
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                    mapping[v]
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                ]  # toggle that dimension, because if v had appeared even times before, it becomes odd times now
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            integrals.append(tuple(vector))
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        seen = {}
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        res = 0
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        for i, v in enumerate(integrals):
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            if v in seen:  # we have seen this vector before
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                res = max(res, i - seen[v])  # compare its substring length
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            else:
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                seen[v] = i  # just record the first time each vector appears
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        return res