Binary Tree Paths LeetCode solution in Python

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class Solution:
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    def binaryTreePaths(self, root: Optional[TreeNode]) -> List[str]:
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        # DFS solution
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        output = []
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        stack = [(root, "")]
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        while stack:
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            node, path = stack.pop()
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            path += str(node.val)
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            if not node.left and not node.right:
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                output.append(path)
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            path += "->"
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            if node.left:
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                stack.append((node.left, path))
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            if node.right:
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                stack.append((node.right, path))
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        return output