✅ Preorder Traversal in Binary Search Tree (BST)

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In Preorder traversal, we visit nodes in this order:

Root → Left → Right

It is mainly used to copy or clone a binary tree or save its structure.

🌳 Example Binary Search Tree:

40 / \ 20 60 / \ / \ 10 30 50 70

🔁 Preorder Traversal Step-by-Step:

1. Visit root →
2. Traverse left subtree →
3. Traverse right subtree

🔢 Preorder Traversal Output:

40 → 20 → 10 → 30 → 60 → 50 → 70

📌 Python Code:

class Node: def __init__(self, key): self.left = None self.right = None self.val = key def preorder(root): if root: print(root.val, end=" ") preorder(root.left) preorder(root.right) # Create BST root = Node(40) root.left = Node(20) root.right = Node(60) root.left.left = Node(10) root.left.right = Node(30) root.right.left = Node(50) root.right.right = Node(70) # Preorder Traversal preorder(root)

📌 Key Point:

✅ Preorder traversal starts with the root first.