一、递归实现 1/**2* Definition for binary tree3* struct TreeNode {4* int val;5* TreeNode *left;6* TreeNode *right;7* TreeNode(int x) : val(x), left(NULL), right(NULL) {}8* };9*/10classSolution {11public:12vector<vector<int> > levelOrder(TreeNode *root) {13vector<vector...
return its level order traversal as: [ [3], [9,20], [15,7] ] SOLUTION 1: 使用队列来解决,很直观。注意在每次换层的时候,新建一个List. 1/**2* Definition for binary tree3* public class TreeNode {4* int val;5* TreeNode left;6* TreeNode right;7* TreeNode(int x) { val = x; ...
BFS要更好写一些。 这里每层遍历node时直接用了for,没有用queue,不然还要另起个变量标记 【Solution】 # Definition for a binary tree node.# class TreeNode:# def __init__(self, x):# self.val = x# self.left = None# self.right = NoneclassSolution:deflevelOrder(self,root:TreeNode)->List[...
Given an n-ary tree, return the level order traversal of its nodes' values. Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples). Example 1: Input: root = [1,null,3,2,4,null,5,6] Output: [...
return its zigzag level order traversal as: [ [3], [20,9], [15,7] ] 1. 2. 3. 4. 5. 题目的意思非常直白。层序遍历整个树,可是第一层正序输出。第二层反序输出,第三层正序输出,以此类推。做法有两种:一、仍然採用level-travel,仅仅是引入一个标记,推断是否反转得到的数列; 二、考虑到stack的特...
leetcode 429 N叉树的层序遍历 n-ary-tree-level-order-traversal【ct】,思路:固定写法,记住,while(queue.length)的时候,首选取len,然后设置level数组,对len进行遍历,计算值并存储
这道题和LeetCode笔记:107. Binary Tree Level Order Traversal II是姊妹题,解题思路都是一样的,只是结果要求的顺序是反的,同样有两种方法,也就是经常说到的DFS深度优先遍历和BFS广度优先遍历。 BFS: 广度优先遍历就是一层层地攻略过去,把每一层的所有节点都记录下来再走向下一层。因为每层会有多个节点,不是简...
102. 二叉树的层序遍历 - 给你二叉树的根节点 root ,返回其节点值的 层序遍历 。 (即逐层地,从左到右访问所有节点)。 示例 1: [https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg] 输入:root = [3,9,20,null,null,15,7] 输出:[[3],[9,20],[15,7]]
Leetcode 102. Binary Tree Level Order Traversal 题目描述 题目链接:https://leetcode-cn.com/problems/binary-tree-level-order-traversal/ 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)。 例如: 给定二叉树: [3,9,20,null,null,15,7], 返回其层次遍历结果: 解题方案...
Leetcode Binary Tree Zigzag Level Order Traversal Binary Tree Zigzag Level Order Traversal Given a binary tree, return thezigzag level ordertraversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between)....