34 lines
860 B
Python
34 lines
860 B
Python
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# Time: O(N)
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# Space: O(N)
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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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from collections import deque
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class BSTIterator:
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items = None
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def __init__(self, root: Optional[TreeNode]):
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def inorder(node):
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return inorder(node.left) + [node.val] + inorder(node.right) if node else []
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# In-order traversal of a BST gives us values in
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# sorted order
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self.items = deque(inorder(root))
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def next(self) -> int:
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return self.items.popleft()
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def hasNext(self) -> bool:
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return len(self.items) > 0
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# Your BSTIterator object will be instantiated and called as such:
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# obj = BSTIterator(root)
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# param_1 = obj.next()
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# param_2 = obj.hasNext()
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