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O(n) time and O(n) space using queue.

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Lines changed: 6 additions & 8 deletions

Original file line number	Diff line number	Diff line change
`@@ -20,26 +20,24 @@`
`20`	`20`
`21`	`21`	`Note that an empty tree is represented by NULL, therefore you would see the expected output (serialized tree format) as [], not null.`
`22`	`22`	`"""`
`23`		`-`
`24`		`-`
`25`	`23`	`# Definition for a binary tree node.`
`26`	`24`	`# class TreeNode:`
`27`	`25`	`# def __init__(self, val=0, left=None, right=None):`
`28`	`26`	`# self.val = val`
`29`	`27`	`# self.left = left`
`30`	`28`	`# self.right = right`
`31`	`29`	`class Solution:`
`32`		`- def searchBST(self, root: TreeNode, val: int) -> TreeNode:`
`33`		`- if not root:`
`34`		`- return None`
	`30`	`+ def searchBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:`
	`31`	`+ if not root: return None`
`35`	`32`	`q = collections.deque()`
`36`	`33`	`q.append(root)`
`37`	`34`	`while q:`
`38`	`35`	`node = q.popleft()`
`39`	`36`	`if node.val == val:`
`40`	`37`	`return node`
`41`		`- if node.left:`
`42`		`- q.append(node.left)`
`43`		`- if node.right:`
	`38`	`+ elif node.val < val and node.right:`
`44`	`39`	`q.append(node.right)`
	`40`	`+ else:`
	`41`	`+ if node.left:`
	`42`	`+ q.append(node.left)`
`45`	`43`	`return None`

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