[Lintcode]73. Construct Binary Tree from Preorder and Inorder Traversal/[Leetcode]105. Construct Bin...-优快云博客

本文介绍了一种通过给定的先序和中序遍历序列来构建二叉树的方法，使用递归算法实现，并提供了一个Python代码示例。这种方法在处理树结构的数据时非常有用。

73. Construct Binary Tree from Preorder and Inorder Traversal/105. Construct Binary Tree from Preorder and Inorder Traversal

本题难度: Medium
Topic: Binary Tree

Description

Given preorder and inorder traversal of a tree, construct the binary tree.

Example
Example 1:
Input: [], []
Output: null

Example 2:
Input: in-order = [1,2,3], pre-order = [2,1,3]
Output:

  2
 / \
1   3

Notice
You may assume that duplicates do not exist in the tree.

我的代码

"""
Definition of TreeNode:
class TreeNode:
    def __init__(self, val):
        self.val = val
        self.left, self.right = None, None
"""

class Solution:
    """
    @param inorder: A list of integers that inorder traversal of a tree
    @param postorder: A list of integers that postorder traversal of a tree
    @return: Root of a tree
    """
    def buildTree(self, preorder, inorder):
        # write your code here
        if preorder and inorder:
            res = TreeNode(preorder[0])
            index = inorder.index(preorder.pop(0))
            res.left = self.buildTree(preorder,inorder[0:index])
            res.right = self.buildTree(preorder,inorder[index+1:])
            return res
        else:
            return None

思路
递归

转载于:https://www.cnblogs.com/siriusli/p/10380898.html