LC 1008 [M] Construct Binary Search Tree from Preorder Traversal - ALawliet/algorithms GitHub Wiki
# 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 Solution:
def bstFromPreorder(self, preorder: List[int]) -> TreeNode:
root = TreeNode(preorder[0])
stack = [root]
for x in preorder[1:]:
node = TreeNode(x)
if node.val < stack[-1].val:
stack[-1].left = node
else:
while stack and node.val > stack[-1].val:
last = stack.pop()
last.right = node
stack.append(node)
return root