Longest Mountain in Array LeetCode solution in Python

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class Solution:
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    def longestMountain(self, arr: List[int]) -> int:
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        if len(arr) < 3:
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            return 0
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        max_up, max_down = [1 for _ in arr], [1 for _ in arr]
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        for i, x in enumerate(arr):
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            if i == 0:
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                continue
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            if x > arr[i - 1]:
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                max_up[i] = max_up[i - 1] + 1
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        for j, y in reversed(list(enumerate(arr))):
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            if j == len(arr) - 1:
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                continue
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            if y > arr[j + 1]:
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                max_down[j] = max_down[j + 1] + 1
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        return max(
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            x + y - 1 if x > 1 and y > 1 else 0 for x, y in zip(max_up, max_down)
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        )