Title Description
And enter the result in a preorder traversal of a binary tree in preorder traversal of the binary tree a rebuild. Suppose Results preorder traversal order and input of duplicate numbers are free. Before entering e.g. preorder traversal sequence {1,2,4,7,3,5,6,8} and {4,7,2,1,5,3,8,6} order traversal sequence, and the reconstructed binary tree return.
Solution one: recursion
# -*- coding:utf-8 -*-
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def reConstructBinaryTree(self, pre, tin):
# 边界条件
if not pre or not tin:
return None
# 前序根节点和中序索引
root = TreeNode(pre.pop(0))
index = tin.index(root.val)
root.left = self.reConstructBinaryTree(pre, tin[:index])
root.right = self.reConstructBinaryTree(pre, tin[index + 1:])
return root