Lec 20 Trees

• Root node is the start of a tree
• Nodes may contain data
  • Can point to any number of child nodes
• No cycling permitted
• Leaf nodes: nodes with no children
• Multiple nodes should not point to the same child node
• TREE:

from typing import Optional, TypeVar, Generic

T = TypeVar('T')

class Node(Generic[T]):
    def __init__(self, data: T) -> None:
        self.data = data
        self.children: list[TreeNode[T]] = []

class Tree(Generic[T]):
    def __init__(self) -> None:
        self.root: Optional[TreeNode[T]] = None

    def __str__(self) -> str:
        return _str_recursive_helper(self.root)

    def _str_recursive_helper(self, curr_node: TreeNode[T]) -> str:
        # base case
        if self.root is None:
            return "*"
        # recursive


entry_way = Node("Entry way")
building: Tree[str] = Tree()
building.root = entry_way

living_room = Node("Living room")
entry_way.children.append(living_room)