Preorder Traversal Problem Statement

You are provided with the root node of a binary tree comprising N nodes. Your objective is to output its preorder traversal. Preorder traversal of a binary tree is performed by visiting nodes in the following sequence:

1- Visit the root node. 2- Traverse all nodes in the left subtree of the root node. 3- Traverse all nodes in the right subtree of the root node.

Example:

Input:

The elements are provided in level order format. Input consists of space-separated values of nodes in a single line, substituting -1 for null nodes. For example, the input for the depicted tree is: 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output:

[1, 2, 4, 7, 3, 5, 6]

Explanation:

For the given binary tree, the preorder traversal results in [1, 2, 4, 7, 3, 5, 6].

Constraints:

1 ≤ T ≤ 10

1 ≤ N ≤ 10^4

1 ≤ nodeVal ≤ 10^9

Time limit: 1 sec

Note:

You are not required to print anything; the printing is handled separately. Focus on implementing the function only.

Question

Preorder Traversal Problem Statement

You are provided with the root node of a binary tree comprising N nodes. Your objective is to output its preorder traversal. Preorder traversal of a binary tree is performed by visiting nodes in the following sequence:

1- Visit the root node.
2- Traverse all nodes in the left subtree of the root node.
3- Traverse all nodes in the right subtree of the root node.

Example:

Input:

The elements are provided in level order format. Input consists of space-separated values of nodes in a single line, substituting -1 for null nodes.

For example, the input for the depicted tree is:
1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1

Output:

[1, 2, 4, 7, 3, 5, 6]

Explanation:

For the given binary tree, the preorder traversal results in [1, 2, 4, 7, 3, 5, 6].

Constraints:

1 ≤ T ≤ 10
1 ≤ N ≤ 10^4
1 ≤ nodeVal ≤ 10^9

Time limit: 1 sec

Note:

You are not required to print anything; the printing is handled separately. Focus on implementing the function only.

Accepted Answer

Implement a function to perform preorder traversal on a binary tree given the root node.

Create a recursive function to traverse the tree in preorder fashion.
Visit the root node, then recursively traverse left subtree, followed by right subtree.
Store the visited nodes in an array and return the array as the result.
Example: For the input tree [1, 2, 3, 4, -1, 5, 6, -1, 7, -1, -1, -1, -1, -1, -1], the preorder traversal output should be [1, 2, 4, 7, 3, 5, 6].