［抄题］: Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following [1,2,2,null,3,null,3] is not: 1 / \ 2 2 \ \ 3…

二叉树(Binary Tree)是最简单的树形数据结构,然而却十分精妙.其衍生出各种算法,以致于占据了数据结构的半壁江山.STL中大名顶顶的关联容器--集合(set).映射(map)便是使用二叉树实现.由于篇幅有限,此处仅作一般介绍(如果想要完全了解二叉树以及其衍生出的各种算法,恐怕要写8~10篇). 1)二叉树(Binary Tree) 顾名思义,就是一个节点分出两个节点,称其为左右子节点:每个子节点又可以分出两个子节点,这样递归分叉,其形状很像一颗倒着的树.二叉树限制了每个节点最多有两个子节…

遍历二叉树   traversing binary tree 线索二叉树 threaded binary tree 线索链表 线索化 1. 二叉树3个基本单元组成:根节点.左子树.右子树 以L.D.R分别表示遍历左子树.访问根节点.遍历右子树 可能的情况6种 排列A3 2 LDR LRD DLR DRL RLD RDL 若限定先左后右 LDR LRD  中根序遍历  后根序遍历 DLR  先根序遍历 先/中/后 序遍历…

1.二叉树(Binary Tree) 是n(n>=0)个结点的有限集合,该集合或者为空集(空二叉树),或者由一个根节点和两棵互不相交的,分别称为根节点的左子树和右子树的二叉树组成.  2.特数二叉树 1)斜二叉树 所有的结点都只有左子树的二叉树叫做左斜树 所有的结点都只有右子树的二叉树叫做右斜树 相当于链表,所以线性结构可以理解为是树的一种极其特殊的表现形式 2)满二叉树(完美二叉树) 所有分支结点都存在左子树和右子树. 所有叶子结点都在同一层 3)完全二叉树 对树按照上->下,左->右…

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 2 / \ / \ 3 4 4 3 But the following [1,2,2,null,3,null,3] is not: 1 / \ 2 2 \ \ 3 3 Not…

Given preorder and inorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. For example, given preorder = [3,9,20,15,7] inorder = [9,3,15,20,7] Return the following binary tree: 3 / \ 9 20…

Given inorder and postorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. For example, given inorder = [9,3,15,20,7] postorder = [9,15,7,20,3] Return the following binary tree: 3 / \ 9 2…

Invert a binary tree. Example: Input: 4 / \ 2 7 / \ / \ 1 3 6 9 Output: 4 / \ 7 2 / \ / \ 9 6 3 1 Trivia:This problem was inspired by this original tweet by Max Howell: Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t…

Given an integer array with no duplicates. A maximum tree building on this array is defined as follow: The root is the maximum number in the array. The left subtree is the maximum tree constructed from left part subarray divided by the maximum number…

Print a binary tree in an m*n 2D string array following these rules: The row number m should be equal to the height of the given binary tree. The column number n should always be an odd number. The root node's value (in string format) should be put i…