Binary Tree Nodes

Advanced SELECT

Question Link

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

1 Leaf
2 Inner
3 Leaf
5 Root
6 Leaf
8 Inner
9 Leaf

Explanation

The Binary Tree below illustrates the sample:

SELECT
    N,
    CASE 
        WHEN P IS NULL THEN 'Root' 
        WHEN N NOT IN (SELECT DISTINCT P FROM BST WHERE P IS NOT NULL) THEN 'Leaf'
        ELSE 'Inner'
    END AS node
FROM BST
ORDER BY N