Maximum Alternating Subsequence Sum LeetCode solution in Python

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# Runtime: 2571 ms (Top 53.06%) | Memory: 28.4 MB (Top 82.81%)
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class Solution:
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    def maxAlternatingSum(self, nums: List[int]) -> int:
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        ans = 0
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        direction = "down"
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        n = len(nums)
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        for i in range(n - 1):
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            if direction == "down" and nums[i] >= nums[i + 1]:
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                ans += nums[i]
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                direction = "up"
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            elif direction == "up" and nums[i] <= nums[i + 1]:
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                ans -= nums[i]
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                direction = "down"
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        if direction == "up":
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            return ans
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        return ans + nums[-1]