https://leetcode.com/problems/binary-tree-preorder-traversal/ 题意分析: 前序遍历一棵树,递归的方法很简单。那么非递归的方法呢。 题目思路: 前序遍历的顺序是先遍历根节点,再遍历左子树,最后遍历右子树。递归的方法很直观。非递归的方法是利用栈来实现,后进先出,先放右子树进入栈。代码给的是非递归的方法。
class Solution(object): def _preorderTraversal(self, root, result): if root: result.append(root.val) self._preorderTraversal(root.left, result) self._preorderTraversal(root.right, result) def preorderTraversal(self, root): """ :type root: TreeNode :rtype: List[int] """ if root ==...
在Python语言中,可以通过递归或迭代的方式实现PreOrder树遍历。 递归实现PreOrder树遍历的代码如下: 代码语言:txt 复制 class TreeNode: def __init__(self, val=0, left=None, right=None): self.val = val self.left = left self.right = right def pre_order_traversal(root): if root is None: ...
4. Binary Tree Preorder Traversal Given a binary tree, return thepreordertraversal 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: Python版本 class Solution: # @par...
LeetCode 589. N-ary Tree Preorder Traversal-多子节点树前序遍历–递归,迭代–反向压栈–C++解法 LeetCode题解专栏:LeetCode题解 我做的所有的LeetCode的题目都放在这个专栏里,大部分题目C++和Python的解法都有。 题目地址:N-ary Tree Preorder Traversal - Le...[...
Binary Tree Postorder Traversal 二叉树的后序遍历 -python 题目 给定一个二叉树,返回它的 后序 遍历。 链接:https://leetcode.com/problems/binary-tree-postorder-traversal/ Given a binary tree, return the postorder traversal of its nodes’ values. Example: Input: [1,null,2,3] 1 ......
144. Binary Tree Preorder Traversal刷题笔记 问题描述前序遍历。注意嵌套函数里的list应该用append而不是+=来添加元素 # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val...
leetcode 1008 Construct Binary Search Tree from Preorder Traversal 1.题目描述 2.解题思路 3.Python代码 1.题目描述 返回与给定先序遍历 preorder 相匹配的二叉搜索树(binary search tree)的根结点。 (回想一下,二叉搜索树是二叉树的一种,其每个节点都满足以下规则,对于 node.left 的任...【...
(root.value, end=' ') preorder_traversal(root.left) preorder_traversal(root.right) # 示例使用 inorder = ['a', '+', 'b', '*', 'c'] root = build_expression_tree(inorder) print("PostOrder Expression:") postorder_traversal(root) p...
Pre-order traversal in a tree Previous Quiz Next In this traversal method, the root node is visited first, then the left subtree and finally the right subtree. We start from A, and following pre-order traversal, we first visit A itself and then move to its left subtree B. B is also...