Binary Tree Nodes — HackerRank Advanced SQL

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:

Solution

select N, 
case when P is Null then "Root"
     when find_in_set(N, (select group_concat(P) as inner_or_root from BST)) > 0 then concat("Inner")
     else "Leaf"
end 
from BST 
order by N