Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? class Solution { public: vector<int> preor…

144. Binary Tree Preorder Traversal Difficulty: Medium Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it it…

144. Binary Tree Preorder Traversal 前序的非递归遍历:用堆来实现 如果把这个代码改成先向堆存储左节点再存储右节点,就变成了每一行从右向左打印 如果用队列替代堆,并且先存储左节点,再存储右节点,就变成了逐行打印 class Solution { public: vector<int> preorderTraversal(TreeNode* root) { vector<int> result; if(root == NULL) return res…

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…

Binary Tree Preorder Traversal Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 解法一:递归 /** *…

Binary Tree Preorder Traversal Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? Solution: 递归…

详见:剑指 Offer 题目汇总索引:第6题 Binary Tree Postorder Traversal            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]. Note: Recursive solution is trivial, could…

二叉树的非递归前序遍历,大抵是很多人信手拈来.不屑一顾的题目罢.然而因为本人记性不好.基础太差的缘故,做这道题的时候居然自己琢磨出了一种解法,虽然谈不上创新,但简单一搜也未发现雷同,权且记录,希望于人于己皆有帮助. 估计能看到这里的读者,都是见过题目的,但还是链接原题在此:Binary Tree Preorder Traversal 二话不说,直接上代码: /** * Definition for binary tree * public class TreeNode { * int val;…

Binary Tree Preorder Traversal Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3},   1    \     2    /   3return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively?…

Binary Tree Preorder Traversal My Submissions QuestionEditorial Solution Total Accepted: 119655 Total Submissions: 300079 Difficulty: Medium Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree {1,#,…

原题 Binary Tree Preorder Traversal 没什么好说的... 二叉树的前序遍历,当然如果我一样忘记了什么是前序遍历的..  啊啊.. 总之,前序.中序.后序,是按照根的位置来决定的,根首先访问,是前序. /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(N…

Binary Tree Preorder Traversal Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. c++版: /** * Definition for binary tree * struct TreeNode { * int val; * TreeNod…

Given an n-ary tree, return the preorder traversal of its nodes' values. For example, given a 3-ary tree: Return its preorder traversal as: [1,3,5,6,2,4]. Note: Recursive solution is trivial, could you do it iteratively? 这道题让我们求N叉树的前序遍历,有之前那道Binary T…

题目:Binary Tree Preorder Traversal 二叉树的前序遍历,同样使用栈来解,代码如下: struct TreeNode { int val; TreeNode* left; TreeNode* right; TreeNode(int x): val(x), left(NULL),right(NULL) {} }; vector<int> preorderTraversal(TreeNode *root) //非递归的前序遍历(用栈实现) { if (NULL == r…

[144-Binary Tree Preorder Traversal(二叉树非递归前序遍历)] [LeetCode-面试算法经典-Java实现][全部题目文件夹索引] 原题 Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solut…

589. N叉树的前序遍历 589. N-ary Tree Preorder Traversal LeetCode589. N-ary Tree Preorder Traversal 题目描述 给定一个 N 叉树,返回其节点值的前序遍历. 例如,给定一个 3 叉树 : 返回其前序遍历: [1,3,5,6,2,4]. 说明: 递归法很简单,你可以使用迭代法完成此题吗? Java 实现 Iterative Solution import java.util.LinkedList; import ja…

problem 589. N-ary Tree Preorder Traversal N叉树的前序遍历 首先复习一下树的4种遍历,前序.中序.后序和层序.其中,前序.中序和后序是根据根节点的顺序进行区分和命名的. 层序遍历,即是按树的层从上到下.从左到右进行遍历. 参考 1. Leetcode_easy_589. N-ary Tree Preorder Traversal; 2. Grandyang; 完…

Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. 二叉树的前序遍历,根节点→左子树→右子树 解题思路一: 递归实现,JAVA实现如下: public List<Integer> preorderTraversal(TreeNode root) { List<I…

题目描述: Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. 解题思路: 这个问题最简单的方法是使用递归,但是题目规定不能使用,得使用迭代的方法. 那么我们考虑使用栈来实现. 思路是每次遍历这节点,把该点的值放入list中,然后把该点的右孩子放入栈中,并将当前点设置为左…

题目: Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 提示: 首先需要明确前序遍历的顺序,即:节点 -> 左孩子 -> 右孩子,这一…

Given a binary tree, return the preorder traversal of its nodes' values. Example: Input: [,,] \ / Output: [,,] Follow up: Recursive solution is trivial, could you do it iteratively? 方法一:使用迭代(C++) vector<int> preorderTraversal(TreeNode* root) { vecto…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? Subscribe to see which companies asked this…

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]. Note: Recursive solution is trivial, could you do it iteratively? 递归 : class Solution { private List<Intege…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 树的遍历,最常见的有先序遍历,中序遍历,后序遍历和层序遍历,它们用递归实现起来都非常的简…

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] Solution 1: # Definition for a binary tree node. # class TreeNode: # def __init__(self, x): # self.val = x # self.left = N…

作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 递归 迭代 日期 题目地址:https://leetcode.com/problems/binary-tree-preorder-traversal/#/description 题目描述 Given a binary tree, return the preorder traversal of its nodes' values. For exampl…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. 代码如下: /** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNod…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 求前序遍历,要求不用递归.     使用双向队列.   /** * Definition…

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? ---------------------------------------------------…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 一般我们提到树的遍历,最常见的有先序遍历,中序遍历,后序遍历和层序遍历,它们用递归实现起…