traversal专题

N-ary Tree Level Order Traversal

N-ary Tree Level Order Traversal

Input: root = [1,null,3,2,4,null,5,6]Output: [[1],[3,2,4],[5,6]] 思路：就是一个queue的level order 收集； /*// Definition for a Node.class Node {public int val;public List<Node> children;public Node() {}pu
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leetcode 刷题之路 4 Binary Tree Level Order Traversal

leetcode 刷题之路 4 Binary Tree Level Order Traversal

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
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LeetCode | Binary Tree Zigzag Level Order Traversal

LeetCode | Binary Tree Zigzag Level Order Traversal

二叉树Z型输出 Given a binary tree, return the zigzag level order traversal of its nodes’ values. (ie, from left to right, then right to left for the next level and alternate between). For example: Given
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LeetCode | Binary Tree Postorder Traversal

LeetCode | Binary Tree Postorder Traversal

后序遍历，当然，，，用栈实现 后序遍历的关键在于从左孩子回到根节点和从右孩子回到跟节点。 如果是从左回的，要继续向右。如果是从右边回来的（表明左右孩子已经遍历结束）这时候就需要将自身输出。 具体到代码上，就是使用一个q指针，用于保存上一个走过的节点（确切的说应该是输出的节点）。 然后从栈顶取出元素的时候，判断p->right==q? 来决定它是从哪个方向回来的~ 完成使命~~ 注释里面
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LeetCode | Binary Tree Inorder Traversal

LeetCode | Binary Tree Inorder Traversal

Given a binary tree, return the inorder traversal of its nodes’ values. For example: Given binary tree [1,null,2,3], 1 \ 2 / 3 return [1,3,2]. Note: Recursive solution is trivial, could you
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LeetCode | Binary Tree Preorder Traversal

LeetCode | Binary Tree Preorder Traversal

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
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105. Construct Binary Tree from Preorder and Inorder Traversal 递归构建树

105. Construct Binary Tree from Preorder and Inorder Traversal 递归构建树

已知树的先序和中序遍历结果，构建原树 先序可以确定根节点，在中序遍历中找到与根节点对应的数值的索引，其左侧为左子树 ，右侧为右子树。递归构建； 需要几个参数，先序遍历的起始索引（只确定根节点），中序遍历的起始索引，中序遍历的截止索引（起始到终止索引为子树的范围） public class Solution {public TreeNode buildTree(int[]
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[leetcode] 107. Binary Tree Level Order Traversal II

[leetcode] 107. Binary Tree Level Order Traversal II

Binary Tree Level Order Traversal II 描述 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
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[leetcode] 102. Binary Tree Level Order Traversal

[leetcode] 102. Binary Tree Level Order Traversal

Binary Tree Level Order Traversal 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
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Binary Tree Postorder Traversal-二叉树的后序遍历

Binary Tree Postorder Traversal-二叉树的后序遍历

原题： Given a binary tree, return the postorder traversal of its nodes' values. =>给定一个二叉树，给出后序遍历的所有节点值 For example: =>例如 Given binary tree {1,#,2,3}, =>给定一个二叉树{1，#，2,3} 1\2/3 return [3,2,1
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Binary Tree Preorder Traversal--二叉树的先序遍历

Binary Tree Preorder Traversal--二叉树的先序遍历

原题： Given a binary tree, return the preorder traversal of its nodes' values. =>给出一个二叉树，返回先序遍历的所有的节点值 For example: 例如： Given binary tree {1,#,2,3}, 给出下面的二叉树 1\2/3 return [1,2,3]. 返回[1,2,3]
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【LeetCode】Construct Binary Tree from Preorder and Inorder Traversal 根据先序序列和中序序列恢复二叉树

【LeetCode】Construct Binary Tree from Preorder and Inorder Traversal 根据先序序列和中序序列恢复二叉树

题目：Construct Binary Tree from Preorder and Inorder Traversal <span style="font-size:18px;">/**LeetCode * 题意：给定一个二叉树的先序遍历和中序遍历的序列，重建二叉树* 思路：先序遍历的第一个节点是父节点，中序遍历从第一个节点到父节点的都是父节点的左子树，父节点后面的都是父节点的右子树*
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Morris Traversal-常量空间下遍历二叉树

Morris Traversal-常量空间下遍历二叉树

通常遍历二叉树有前序（preorder）、中序（inorder）、后序（postorder）遍历有两个常用的方法：一是递归(recursive)，二是使用栈实现的迭代版本(stack+iterative)。这两种方法都是O(n)的空间复杂度（递归本身占用stack空间或者用户自定义的stack）。递归的方法很简单，栈使用的方法见楼主另一篇文章，栈和队列在遍历二叉树中的使用。文章总结了常见的几种思路
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Construct Binary Tree from Preorder and Inorder Traversal问题及解法

Construct Binary Tree from Preorder and Inorder Traversal问题及解法

问题描述： Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 问题分析： 已知树的先序和中序遍历的结果，我们可以依此来分别构建左子树、右子树和树根，递归求解即可
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Binary Tree Zigzag Level Order Traversal问题及解法

Binary Tree Zigzag Level Order Traversal问题及解法

问题描述： Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). 示例： Given binary t
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Binary Tree Level Order Traversal问题及解法

Binary Tree Level Order Traversal问题及解法

问题描述： Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). 示例： Given binary tree [3,9,20,null,null,15,7], 3/ \9 20/ \15 7
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Binary Tree Inorder Traversal问题及解法

Binary Tree Inorder Traversal问题及解法

问题描述： Given a binary tree, return the inorder traversal of its nodes' values. 示例： Given binary tree [1,null,2,3], 1\2/3 return [1,3,2]. 问题分析： 利用二叉树的先序遍历，先遍历左子树，后父节点，最后遍历右子树。 过程详见
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leetcode No106. Construct Binary Tree from Inorder and Postorder Traversal

leetcode No106. Construct Binary Tree from Inorder and Postorder Traversal

Question： Given inorder and postorder traversal of a tree, construct the binary tree. 根据树的中序遍历和后序遍历构建二叉树 Algorithm： 中序遍历：左-根-右 后序遍历：左-右-根 举个例子 中序遍历：DBEAFCG 后序遍历：DEBFGCA 1、后序遍历的最后一
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leetcode No105. Construct Binary Tree from Preorder and Inorder Traversal

leetcode No105. Construct Binary Tree from Preorder and Inorder Traversal

Question: Given preorder and inorder traversal of a tree, construct the binary tree. 根据树的前序遍历和中序遍历，构建二叉树 Algorithm： 前序遍历：根-左-右 中序遍历：左-根-右 举个例子 前序遍历：ABDECFG 中序遍历：DBEAFCG
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leetcode No94. Binary Tree Inorder Traversal

leetcode No94. Binary Tree Inorder Traversal

Question: Given a binary tree, return the inorder traversal of its nodes' values. For example: Given binary tree [1,null,2,3], 1\2/3 return [1,3,2]. Note: Recursive solution is trivi
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[LeetCode] Binary Tree Postorder Traversal

[LeetCode] Binary Tree Postorder Traversal

Given a binary tree, return the postorder traversal of its nodes’ values. For example: Given binary tree {1,#,2,3}, return [3,2,1]. Note: Recursive solution is trivial, could you do it iterative
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Leetcode 107 Binary Tree Level Order Traversal II（水）

Leetcode 107 Binary Tree Level Order Traversal II（水）

题目连接：Leetcode 107 Binary Tree Level Order Traversal II 解题思路：参考Leetcode 102 和103，只要最后将102中的答案翻转一下即可。 /*** Definition for a binary tree node.* struct TreeNode {* int val;* TreeNode *left;*
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Leetcode 106 Construct Binary Tree from Inorder and Postorder Traversal（二叉树）

Leetcode 106 Construct Binary Tree from Inorder and Postorder Traversal（二叉树）

题目连接：Leetcode 106 Construct Binary Tree from Inorder and Postorder Traversal 解题思路：参考 Leetcode 105。 /*** Definition for a binary tree node.* struct TreeNode {* int val;* TreeNode *left;*
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Leetcode 105 Construct Binary Tree from Preorder and Inorder Traversal（二叉树）

Leetcode 105 Construct Binary Tree from Preorder and Inorder Traversal（二叉树）

题目连接：Leetcode 105 Construct Binary Tree from Preorder and Inorder Traversal 解题思路：p指针在二叉树的中序遍历上移动，inorder[p]即为当前结点的值，然后找到preorder中找到inorder[p]的位置t，根据前序遍历的性质，在preorder中，start~t-1的结点应该是当前结点的左子树，t+1~end的
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Leetcode 103 Binary Tree Zigzag Level Order Traversal（BFS）

Leetcode 103 Binary Tree Zigzag Level Order Traversal（BFS）

题目连接：Leetcode 103 Binary Tree Zigzag Level Order Traversal 解题思路：与Leetcode 102 一样，使用BFS层次遍历二叉树，不同的是，对于奇数层，要翻转一下结点顺序。 /*** Definition for a binary tree node.* struct TreeNode {* int val;* Tree
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LeetCode 题解（155）: Construct Binary Tree from Inorder and Postorder Traversal

LeetCode 题解（155）: Construct Binary Tree from Inorder and Postorder Traversal

题目： Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 题解： 递归。 C++版： class Solution {public:TreeNode*
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