102. 二叉树的层次遍历 102. Binary Tree Level Order Traversal 题目描述 给定一个二叉树,返回其按层次遍历的节点值. (即逐层地,从左到右访问所有节点). 每日一算法2019/5/11Day 8LeetCode102. Binary Tree Level Order Traversal 例如: 给定二叉树: [3,9,20,null,null,15,7], 3 / \ 9 20 / \ 15 7 返回其层次遍历结果: [ [3], [9,20], [15…

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…

［抄题］: 给出一棵二叉树,返回其节点值的层次遍历(逐层从左往右访问) ［思维问题］: ［一句话思路］: 用queue存每一层 ［输入量］:空: 正常情况:特大:特小:程序里处理到的特殊情况:异常情况(不合法不合理的输入): ［画图］: ［一刷］: 每一层level存的东西都是不一样的,所以要在queue非空的循环中再新建.不要当成全局变量. root为空时,返回result空数组,而不是null四个字母 stack用pop 弹出来,queue用poll 拉出来,想想也比较形象.root非空用n…

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…

［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…

描述 给出一棵二叉树,返回其节点值的层次遍历(逐层从左往右访问) 样例 给一棵二叉树 {3,9,20,#,#,15,7} : 3 / \ 9 20 / \ 15 7 返回他的分层遍历结果: [ [3], [9,20], [15,7] ] 挑战 挑战1:只使用一个队列去实现它 挑战2:用BFS算法来做 代码 GitHub 的源代码,请访问下面的链接: https://github.com/cwiki-us/java-tutorial/blob/master/src/test/java/com/os…

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,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its bottom-up level order tra…

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,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its bottom-up level order tr…

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

Binary Tree Level Order Traversal 题目描述: 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,#,#,15,7}, 3 / \ 9 20 / \ 15 7 return its level order…