Prerequisites : Binary Trees.
Problem: Print nodes of given binary tree in preorder manner.
Solution Approach: Preorder traversal is one of the fundamental depthfirst traversal methods for binary trees. In a binary tree, each node has at most two children: a left child and a right child. Preorder traversal follows the order of visiting nodes in the following sequence:

 Visit the Root Node:
 Start at the root of the tree.
 Process/visit the data (or perform an operation) associated with the root node.
 Visit the Root Node:

 Traverse the Left Subtree:
 Recursively perform a preorder traversal on the left subtree of the current node.
 For each node in the left subtree, repeat steps 1 and 2.
 Traverse the Left Subtree:

 Traverse the Right Subtree:
 Recursively perform a preorder traversal on the right subtree of the current node.
 For each node in the right subtree, repeat steps 1 and 2.
 Traverse the Right Subtree:
Time complexity: O(N), where N is the number of nodes in the tree. Each node is visited once.
Space complexity: O(1), as we donâ€™t need any extra space.