Binary Tree Maximum Path Sum LeetCode solution in Python

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class Solution:
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    def maxPathSum(self, root: Optional[TreeNode]) -> int:
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        self.res = root.val
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        def solving(root):
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            if not root:
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                return 0
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            current = root.val
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            sleft, sright = float("-inf"), float("-inf")
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            if root.left:
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                sleft = solving(root.left)
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                if sleft >= 0:
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                    current += sleft
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            if root.right:
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                sright = solving(root.right)
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                if sright >= 0:
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                    current += sright
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            if current > self.res:
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                self.res = current
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            return max(root.val, root.val + sleft, root.val + sright)
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        solving(root)
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        return self.res