题意:给一棵树,求其先根遍历的结果. 思路: (1)深搜法: /** * 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<int> preorderT…

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?…

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 preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3} 1 \ 2 / 3 return [1,2,3]. 前序遍历二叉树,只不过题目的要求是尽量不要使用递归,当然我还是先用递归写了一个: /** * Definition for a binary tree node. * struct TreeNode { * int val…

原题地址:http://oj.leetcode.com/problems/binary-tree-preorder-traversal/ 题意:这题用递归比较简单.应该考察的是使用非递归实现二叉树的先序遍历.先序遍历的遍历顺序是:根,左子树,右子树. 解题思路:如果树为下图: 1 /     \ 2         3 /     \    /    \ 4       5  6     7 使用一个栈.步骤为: 一,先遍历节点1,并入栈,如果有左孩子,继续遍历并入栈,一直到栈为{1,2,4}.…

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…

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…

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…

先给出递归版本的实现方法,有时间再弄个循环版的.代码如下: /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: vector<int> postorderTraversal…

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 =…