SYSU_xiandan的博客

Problem: Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. 题意是求二叉树的最大深度。有两种方法，第

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node.

Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 由题意得，这题是给出一个二叉树的前序和中序序列，然后要求构造这样的一个二叉树。用递归的方法比较容易懂和好写，所

Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 题意是给出二叉树的中序和后序，然后构造这个二叉树，这题和105基本是一样的思想和框架，就是区间不太一

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example, Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \

Given a binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 which represents the number 123. Find the tota

Given an integer n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example, Given n = 3, your program should return all 5 unique BST's shown below. 1

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. For this problem, a height-balanced binary tree is defined as a binary tree in which th

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 diffe

Given a binary tree, return the postorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [3,2,1]. 题意是要求二叉树的后序遍历，那

今天复习到了二叉树，首先是了解一下二叉树的一下定义： 二叉树是每个节点最多有两个子树的树结构，通常称为左/右子树。如图所示： 其中深度Depth可以理解为层数，那么第i层则有2^(i-1)那么多的节点。其中没有左右子树的节点称为叶节点，而 其他的称为根节点。例如值为8~15的节点就是叶子节点。 而树的类型也有很多种，其中基本的有： 1.完全二叉树——假如一棵树的最大深度为D，那么1到

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example: Given binary tree [3,9,20,null,null,15,7], 3 / \ 9 20

Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree [3,9,20,null,null,15,

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example: Given binary

Given a binary tree, return the inorder traversal of its nodes' values. For example: Given binary tree [1,null,2,3], 1 \ 2 / 3 return [1,3,2]. 题意是对二叉树进行中序遍历，

Problem: Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Problem: 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 / \ / \

Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree [1,null,2,3], 1 \ 2 / 3 return [1,2,3]. 题意是要先序遍历一个二叉树

Given an array where elements are sorted in ascending order, convert it to a height balanced BST. 由题意得，给出一个递增的序列，然后求出它的高度平衡的二叉搜索树。题目比较简单，就用二分法，每次取序列的一半来作为子树的根的结点值，用递归的方法就可以实现，代码如下。 Code(LeetCo

Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only nodes with keys less than the node's key.Th