public List<Integer> preorderTraversal(TreeNode root) { List<Integer> list = new ArrayList<>(); preorderTraversalHelper(root, list); return list; } private void preorderTraversalHelper(TreeNode root, List<Integer> list) { if (root == null) { return; } list.add(root.val); preorderTrav...
1vector<int> preorderTraversal(TreeNode*root) {2vector<int>rVec;3if(!root)4returnrVec;56stack<TreeNode *>st;7st.push(root);8while(!st.empty())9{10TreeNode *tree =st.top();11rVec.push_back(tree->val);12st.pop();13if(tree->right)14st.push(tree->right);15if(tree->left)1...
1/**2* Definition for binary tree3* 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) {13//IMPORTANT: Please reset any...
* 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 { // 递归实现前序遍历 void preorderTraversalRecursive(TreeNode* root, vector<int>& preSe...
LeetCode Binary Tree Preorder Traversal 1.题目 Given a binary tree, return thepreordertraversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 1. 2. 3. 4. 5. return [1,2,3]....
[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...
* TreeNode(int x) { val = x; } * } */publicclassSolution{public List<Integer>preorderTraversal(TreeNode root){ArrayList<Integer>result=newArrayList<Integer>();if(root==null)returnresult;preorder(root,result);returnresult;}privatevoidpreorder(TreeNode root,ArrayList<Integer>result){result.add...
Binary tree traversal: Preorder, Inorder, and Postorder In order to illustrate few of the binary tree traversals, let us consider the below binary tree: Preorder traversal: To traverse a binary tree in Preorder, following operations are carried-out (i) Visit the root, (ii) Traverse the le...
Level order traversal of below binary tree will be: We will use Queue for Level Order traversal. This algorithm is very similar to Breadth first search of graph. 3. Process of Level Order Traversal Create empty queue and pust root node to it. Do the following when queue is not empty Po...
Can you solve this real interview question? Binary Tree Preorder Traversal - Given the root of a binary tree, return the preorder traversal of its nodes' values. Example 1: Input: root = [1,null,2,3] Output: [1,2,3] Explanation: [https://assets.l