树形结构应该是贯穿整个数据结构的一个比较重要的一种结构,它的重要性不言而喻! 讲到树!一般都是讨论二叉树,而关于二叉树的定义以及概念这里不做陈诉,可自行搜索. 在C语言里面需要实现一个二叉树,我们需要申明一个结构体,而关于其结构体的多种方法 这里也不一一列出,我采用比较通用的方法: struct TreeNode{ ElementType Element; struct TreeNode *Left; struct TreeNode *RIght; }; BinaryTree.h: #ifnde…

Given a binary tree, return the preorder traversal of its nodes' values. Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [1,2,3] Follow up: Recursive solution is trivial, could you do it iteratively? 给定一个二叉树,返回它的 前序 遍历. 示例: 输入: [1,null,2,3] 1 \ 2 / 3…

Given a binary tree, return the preorder traversal of its nodes' values. Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [1,2,3] Follow up: Recursive solution is trivial, could you do it iteratively? ---------------------------------------------------…

［抄题］: 给定一个二叉树,像这样收集树节点:收集并移除所有叶子,重复,直到树为空. 给出一个二叉树: 1 / \ 2 3 / \ 4 5 返回 [[4, 5, 3], [2], [1]]. [暴力解法]: 时间分析: 空间分析: ［思维问题］: 觉得要用BFS.不知道用dfs怎么求高度:max(左,右)+1,这是高度的定义吧 只知道怎么摘,不知道要去尝试用数学表示出来:第k层扒下来的叶子节点,高度也是k 不知道怎么把一层的节点都存在一个hashmap中,觉得一个key不是只能存一个value么…

144. 二叉树的前序遍历 144. Binary Tree Preorder Traversal 题目描述 给定一个二叉树,返回它的 前序 遍历. LeetCode144. Binary Tree Preorder Traversal 示例: 输入: [1,null,2,3] 1 \ 2 / 3 输出: [1,2,3] 进阶: 递归算法很简单,你可以通过迭代算法完成吗? Java 实现 Iterative Solution import java.util.LinkedList; import…

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,15,7], 3 / \ 9 20 / \ 15 7 return its bottom-up level or…

Given a binary tree where all the right nodes are either leaf nodes with a sibling (a left node that shares the same parent node) or empty, flip it upside down and turn it into a tree where the original right nodes turned into left leaf nodes. Return…

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 / \ 15 7 return its level order traversal as: [ [3], [9,20], [15,7…

Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom. Example: Input: [1,2,3,null,5,null,4] Output: [1, 3, 4] Explanation: 1 <--- / \ 2 3 <--- \ \ 5 4 <--- 给…

Given a binary tree, return all root-to-leaf paths. Note: A leaf is a node with no children. Example: Input: 1 / \ 2 3 \ 5 Output: ["1->2->5", "1->3"] Explanation: All root-to-leaf paths are: 1->2->5, 1->3 给定一个二叉树,返回所…