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# Runtime: 87 ms (Top 85.77%) | Memory: 16.7 MB (Top 24.56%)
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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class Solution:
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    def searchBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:
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        def search(root):
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            if not root:
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                return None
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            if root.val == val:
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                return root
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            elif root.val < val:
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                ans = search(root.right)
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                if ans:
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                    return ans
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                return None
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            else:
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                ans = search(root.left)
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                if ans:
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                    return ans
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                return None
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        return search(root)