Find Latest Group of Size M LeetCode solution in Python

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class Solution:
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    def findLatestStep(self, arr: List[int], m: int) -> int:
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        n = len(arr)
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        ans = -1
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        if n == m:
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            return m  # just in case
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        #       make in "inverted" array with artificial ends higher then everything between
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        sor = [0 for _ in range(n + 2)]
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        for i in range(n):
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            sor[(arr[i])] = i + 1
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        sor[0] = sor[n + 1] = n + 1
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        #       scan and see, if ones in the middle of space of length m appear
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        #       before ones on its ends,
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        #       and find the latest of such spaces to disappear, if exists
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        for i in range(1, n - m + 2):
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            if all(
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                sor[i - 1] > sor[j] and sor[i + m] > sor[j] for j in range(i, i + m)
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            ):
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                if min(sor[i - 1] - 1, sor[i + m] - 1) > ans:
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                    ans = min(sor[i - 1] - 1, sor[i + m] - 1)
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        return ans