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# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class BSTIterator:
def __init__(self, root: TreeNode):
self.stack=[]
while root:
self.stack.append(root)
root=root.left
def next(self) -> int:
cur=self.stack.pop()
node=cur.right
while node:
self.stack.append(node)
node=node.left
return cur.val
def hasNext(self) -> bool:
return len(self.stack)>0
# Your BSTIterator object will be instantiated and called as such:
# obj = BSTIterator(root)
# param_1 = obj.next()
# param_2 = obj.hasNext()?
