* Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } 解题思路 1.语法: 与二叉树相关的问题, 不要想得太复杂,数据结构抽象如下 根节点 / \ 左子树 右子树 而左子树和右子树又可以看成和上面相同的数据结构, 即树具有递归性质的数据结构, 解决树的问题时,递…

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…

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…

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…

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…

Binary Tree Inorder Traversal Given a binary tree, return the inorder traversal of its nodes' values. Example Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,3,2]. For in-order traversal we all know that firstly we want to go to the lowest level and…

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…

Binary Tree Zigzag Level Order Traversal 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 binary tree {3,9,20,…

原题: Binary Tree Inorder Traversal 和 3月3日(2) Binary Tree Preorder Traversal 类似,只不过变成中序遍历,把前序遍历的代码拿出来,改函数,改一句话位置 AC.…

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…