1.遞歸的思想:通過前序序列找到根節點,然後在中序中分爲左右子樹.
2.index:找到值對應的索引位置返回
3.遞歸函數何時停止的條件很重要
# -*- coding:utf-8 -*-
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
# 返回構造的TreeNode根節點
def reConstructBinaryTree(self, pre, tin):
# write code here
if not pre or not tin:
return None
root=TreeNode(pre[0])
val=tin.index(pre[0])
root.left=self.reConstructBinaryTree(pre[1:val+1],tin[:val])
root.right=self.reConstructBinaryTree(pre[val+1:],tin[val+1:])
return root