173. Binary Search Tree Iterator

LeetCode - The World's Leading Online Programming Learning Platform

# 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 init1(self,root):
        values=[]

        def dfs(node):
            if node:
                dfs(node.left)
                values.append(node)
                dfs(node.right)
        dfs(root)
        return values        

    def __init__(self, root: Optional[TreeNode]):
        self.values=self.init1(root)
        self.idx=0


    def next(self) -> int:
        value=self.values[self.idx].val
        self.idx+=1
        return value

    def hasNext(self) -> bool:
        return self.idx<len(self.values)
        


# Your BSTIterator object will be instantiated and called as such:
# obj = BSTIterator(root)
# param_1 = obj.next()
# param_2 = obj.hasNext()

dfs