Problem Link: http://oj.leetcode.com/problems/balanced-binary-tree/ We use a recursive auxilar function to determine whether a sub-tree is balanced, if the tree is balanced, it also return the depth of the sub-tree. A tree T is balanced if the follow…

Problem Link: https://oj.leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/ The basic idea is same to that for Construct Binary Tree from Inorder and Postorder Traversal. We solve it using a recursive function. First, we…

Problem Link: https://oj.leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/ This problem can be easily solved using recursive method. By given the inorder and postorder lists of the tree, i.e. inorder[1..n] and postorde…

Problem Link: http://oj.leetcode.com/problems/flatten-binary-tree-to-linked-list/ The problem is asking for flatterning a binary tree to linked list by the pre-order, therefore we could flatten tree from the root. For each node, we link it with its n…

Problem Link: https://oj.leetcode.com/problems/validate-binary-search-tree/ We inorder-traverse the tree, and for each node we check if current_node.val > prev_node.val. The code is as follows. # Definition for a binary tree node # class TreeNode: #…

Problem Link: https://oj.leetcode.com/problems/recover-binary-search-tree/ We know that the inorder traversal of a binary search tree should be a sorted array. Therefore, we can compare each node with its previous node in the inorder to find the two…

深度优先搜索 # Definition for a binary tree node.# class TreeNode:#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution:    # @param {TreeNode} root    # @return {string[]}        resultList=[…

#-*- coding: UTF-8 -*- # Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def levelOrderBottom(self, root):   …

#-*- coding: UTF-8 -*-#广度优先遍历# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    tmplist1=[]        def dfsDept…

Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1. 做完了链表系列,这几天开始做树系列.对于解决关于树的问题,递归是一个很…