SQL - Binary Tree Nodes

You are given a table, BST, containing two columns: N and P, where N represents the value of a node in Binary Tree, and P is the parent of N.

Write a query to find the node type of Binary Tree ordered by the value of the node. Output one of the following for each node:

• Root: If node is root node.
• Leaf: If node is leaf node.
• Inner: If node is neither root nor leaf node.

Sample Input

Sample Output

Answer :

SELECT CASE
    WHEN P IS NULL THEN CONCAT(N, ' Root')
    WHEN N IN (SELECT DISTINCT P FROM BST) THEN CONCAT(N, ' Inner')
    ELSE CONCAT(N, ' Leaf')
    END
FROM BST
ORDER BY N ASC