* Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * };*/classSolution {public: vector<int> preorderTraversal(TreeNode*root) { vector<int>result; preorder(root, r...
1/**2* Definition for a binary tree node.3* struct TreeNode {4* int val;5* TreeNode *left;6* TreeNode *right;7* TreeNode(int x) : val(x), left(NULL), right(NULL) {}8* };9*/10classSolution {11public:12vector<int> preorderTraversal(TreeNode*root) {13vector<int>rVec;14pr...
题目地址:https://leetcode.com/problems/binary-tree-preorder-traversal/description/ Given a binary tree, return thepreordertraversal of its nodes' values. Example: Input:[1,null,2,3]1 \ 2 / 3Output:[1,2,3] Follow up:Recursive solution is trivial, could you do it iteratively? 给定一个...
1/**2* Definition for a binary tree node.3* struct TreeNode {4* int val;5* TreeNode *left;6* TreeNode *right;7* TreeNode(int x) : val(x), left(NULL), right(NULL) {}8* };9*/10classSolution {11public:12vector<int> preorderTraversal(TreeNode*root) {13vector<int>rVec;14pr...
Given therootof a binary tree, returnthe preorder traversal of its nodes' values. Example 1: image <pre>Input:root = [1,null,2,3] Output:[1,2,3] </pre> Example 2: <pre>Input:root = [] Output:[] </pre> Example 3:
[TreeNode]()varcurr=rootwhile(stack.nonEmpty||curr!=null){while(curr!=null){stack.push(curr)rs.append(curr.value)curr=curr.left}valnode=stack.pop()curr=node.right}rs.toList}defpreorderTraversalV4(root:TreeNode):List[Int]={if(root==null)returnNilvalrs=ListBuffer.empty[Int]valstack=Stack...
上边的两种解法,空间复杂度都是O(n),利用 Morris Traversal 可以使得空间复杂度变为O(1)。 它的主要思想就是利用叶子节点的左右子树是null,所以我们可以利用这个空间去存我们需要的节点,详细的可以参考94 题中序遍历。 publicList<Integer>preorderTraversal(TreeNoderoot){List<Integer>list=newArrayList<>();Tree...
In our previous post, we saw how to implement a binary search tree in Java and how to insert nodes in binary search tree.In this post, we will talk about the binary tree traversal. We will work on java code for traversing a binary tree in Java. 1. Binary Tree Traversal Binary tree ...
/** * 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> preorderTraversal(TreeNode* root) {...
self.val = val self.left = left self.right = right class Solution: # 递归 def preorderTraversal_1(self, root: TreeNode) -> List[int]: res = [] self.dfs(root, res) return res def dfs(self, node, res): if not node: return ...