Tree Basics

Trees are hierarchical data structures with a root and child nodes. They model natural hierarchies like file systems and organization charts.

Terminology

Tree Terminology

• Root: The top node of the tree (1).
• Edge: The link between two nodes.
• Parent/Child: Node 1 is the parent of 2 and 3.
• Leaf: A node with no children (4, 5, 3).
• Height: The number of edges on the longest path from the node to a leaf.
• Depth: The number of edges from the root to the node.

Binary Tree

Each node has at most 2 children.

class TreeNode:
    def __init__(self, val=0):
        self.val = val
        self.left = None
        self.right = None

Quiz

Key Takeaways

✅ Hierarchical structure - root, children, leaves
✅ Binary tree - at most 2 children per node
✅ Recursive operations - naturally suited for trees

Perfect for hierarchical data like file systems! 🚀