[SQL][HackerRank] Binary Tree Nodes

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Binary Tree Nodes | HackerRank

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, IF(P IS NULL, 'Root', IF((SELECT COUNT(*)  FROM BST WHERE P=B.N)>0, 'Inner', 'Leaf'))  
FROM BST AS B 
ORDER BY N;

 

SELECT N, IF(P IS NULL, 'Root', IF(B.N IN (SELECT P FROM BST), 'Inner', 'Leaf'))  
FROM BST AS B  
ORDER BY N;