LeetCode：144_Binary Tree Preorder Traversal | 二叉树的前序遍历

LeetCode：144_Binary Tree Preorder Traversal | 二叉树的前序遍历 | Medium

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…

lintcode ：Binary Tree Preorder Traversal 二叉树的前序遍历

题目: 二叉树的前序遍历给出一棵二叉树,返回其节点值的前序遍历. 样例给出一棵二叉树 {1,#,2,3}, 1 \ 2 / 3 返回 [1,2,3]. 挑战你能使用非递归实现么? 解题: 通过递归实现,根节点->左节点->右节点 Java程序: /** * Definition of TreeNode: * public class TreeNode { * public int val; * public TreeNode left, right; * public TreeNode(…

【LeetCode】Binary Tree Preorder Traversal(二叉树的前序遍历)

这道题是LeetCode里的第144道题. 题目要求: 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 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? 解题代码: /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x)…

LeetCode 144. Binary Tree Preorder Traversal 二叉树的前序遍历 C++

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…

144 Binary Tree Preorder Traversal 二叉树的前序遍历

给定一棵二叉树,返回其节点值的前序遍历.例如:给定二叉树[1,null,2,3], 1 \ 2 / 3返回 [1,2,3].注意: 递归方法很简单,你可以使用迭代方法来解决吗?详见:https://leetcode.com/problems/binary-tree-preorder-traversal/description/ Java实现: 递归实现: /** * Definition for a binary tree node. * public class T…

Leetcode144. Binary Tree Preorder Traversal二叉树的前序遍历

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 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? 递归: class Solution { public: vector<int> res; vector<int> preorderTraversal(TreeNode* root) { GetAns(root); return res; } void GetAns(TreeNode* root) { if…

144 Binary Tree Preorder Traversal(二叉树先序遍历Medium)

题目意思:二叉树先序遍历,结果存在vector<int>中解题思路:1.递归(题目中说用递归做没什么意义,我也就贴贴代码吧) 2.迭代迭代实现: class Solution { public: vector<int> preorderTraversal(TreeNode* root) { vector<int> ans; if(root){ TreeNode* temp; stack<TreeNode*> s; //利用栈,每次打印栈顶,然后将栈顶弹出…

C++版 - LeetCode 144. Binary Tree Preorder Traversal (二叉树先根序遍历，非递归)

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…

LeetCode：94_Binary Tree Inorder Traversal | 二叉树中序遍历 | Medium

题目:Binary Tree Inorder Traversal 二叉树的中序遍历,和前序.中序一样的处理方式,代码见下: struct TreeNode { int val; TreeNode* left; TreeNode* right; TreeNode(int x): val(x), left(NULL),right(NULL) {} }; vector<int> preorderTraversal(TreeNode *root) //非递归的中序遍历(用栈实现) { if (NULL…

[LeetCode] Binary Tree Preorder Traversal 二叉树的先序遍历

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…

94 Binary Tree Inorder Traversal(二叉树中序遍历Medium)

题目意思:二叉树中序遍历,结果存在vector<int>中解题思路:迭代迭代实现: /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: vector&l…

[Leetcode] Binary tree postorder traversal二叉树后序遍历

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 you do it iteratively? 后序遍历:左孩子->右孩子->根节点后序遍历最关键的是利用一个指针保存前一个访问过的信…

[Leetcode] Binary tree inorder traversal二叉树中序遍历

Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3 return[1,3,2]. Note: Recursive solution is trivial, could you do it iteratively? confused what"{1,#,2,3}"means? > read m…

[LeetCode] N-ary Tree Preorder Traversal N叉树的前序遍历

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…

[LeetCode] 144. Binary Tree Preorder Traversal 二叉树的先序遍历

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…

[LeetCode] Binary Tree Postorder Traversal 二叉树的后序遍历

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 you do it iteratively? 经典题目,求二叉树的后序遍历的非递归方法,跟前序,中序,层序一样都需要用到栈,后续的…

[LeetCode] Binary Tree Inorder Traversal 二叉树的中序遍历

Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,3,2]. Note: Recursive solution is trivial, could you do it iteratively? confused what "{1,#,2,3}" means? > re…

LeetCode——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? 中文:二叉树的前序遍历(根-左-右). 能用非递归实现吗? 递归: public cl…

LeetCode：145_Binary Tree Postorder Traversal | 二叉树后序遍历 | Hard

题目:Binary Tree Postorder Traversal 二叉树的后序遍历,题目要求是采用非递归的方式,这个在上数据结构的课时已经很清楚了,二叉树的非递归遍历不管采用何种方式,都需要用到栈结构作为中转,代码很简单,见下: struct TreeNode { int val; TreeNode* left; TreeNode* right; TreeNode(int x): val(x), left(NULL),right(NULL) {} }; vector<int> preord…

LeetCode: Binary Tree Preorder Traversal 解题报告

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?…

[LeetCode]144. Binary Tree Preorder Traversal二叉树前序遍历

关于二叉树的遍历请看: http://www.cnblogs.com/stAr-1/p/7058262.html /* 考察基本功的一道题,迭代实现二叉树前序遍历 */ public List<Integer> preorderTraversal(TreeNode root) { List<Integer> res = new ArrayList<>(); if (root==null) return res; Stack<TreeNode> stack =…

144. Binary Tree Preorder Traversal (二叉树前序遍历)

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…

[LeetCode] 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? 这题简单,属于课本习题的难度,题目提示说用迭代试试,当然用递归也可以AC的.迭代的时候要…

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