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83 lines
2.2 KiB
Python
83 lines
2.2 KiB
Python
"""
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Illustrate how to implement inorder traversal in binary search tree.
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Author: Gurneet Singh
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https://www.geeksforgeeks.org/tree-traversals-inorder-preorder-and-postorder/
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"""
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class BinaryTreeNode:
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"""Defining the structure of BinaryTreeNode"""
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def __init__(self, data: int) -> None:
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self.data = data
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self.left_child: BinaryTreeNode | None = None
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self.right_child: BinaryTreeNode | None = None
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def insert(node: BinaryTreeNode | None, new_value: int) -> BinaryTreeNode | None:
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"""
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If the binary search tree is empty, make a new node and declare it as root.
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>>> node_a = BinaryTreeNode(12345)
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>>> node_b = insert(node_a, 67890)
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>>> node_a.left_child == node_b.left_child
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True
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>>> node_a.right_child == node_b.right_child
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True
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>>> node_a.data == node_b.data
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True
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"""
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if node is None:
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node = BinaryTreeNode(new_value)
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return node
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# binary search tree is not empty,
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# so we will insert it into the tree
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# if new_value is less than value of data in node,
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# add it to left subtree and proceed recursively
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if new_value < node.data:
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node.left_child = insert(node.left_child, new_value)
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else:
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# if new_value is greater than value of data in node,
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# add it to right subtree and proceed recursively
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node.right_child = insert(node.right_child, new_value)
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return node
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def inorder(node: None | BinaryTreeNode) -> list[int]: # if node is None,return
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"""
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>>> inorder(make_tree())
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[6, 10, 14, 15, 20, 25, 60]
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"""
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if node:
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inorder_array = inorder(node.left_child)
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inorder_array = inorder_array + [node.data]
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inorder_array = inorder_array + inorder(node.right_child)
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else:
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inorder_array = []
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return inorder_array
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def make_tree() -> BinaryTreeNode | None:
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root = insert(None, 15)
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insert(root, 10)
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insert(root, 25)
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insert(root, 6)
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insert(root, 14)
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insert(root, 20)
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insert(root, 60)
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return root
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def main() -> None:
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# main function
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root = make_tree()
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print("Printing values of binary search tree in Inorder Traversal.")
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inorder(root)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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main()
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