Preorder Traversal

Implement a function that performs a preorder traversal of a binary tree and returns the values in the order they were visited. Input format: The first line contains an integer N, the number of nodes in the tree. The next N lines contain three integers: the node value, the left child value, and the right child value, where -1 indicates that the child does not exist. Output format: Output a single line of space-separated integers representing the values in preorder. Example: Input: 4 1 2 3 2 -1 4 3 -1 -1 4 -1 -1 Output: 1 2 4 3