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  3. Advanced Select
  4. Binary Tree Nodes
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Binary Tree Nodes

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  • rahmatNazali
     + 54 comments

    A simple solution using MySQL Case. I hope this helps.

    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

  • tubededentifrice
     + 48 comments

    Easier is better 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;

  • cheftr
     + 5 comments

    Worked for me:

    select n, case when (p is null) then 'Root' when (n in (select p from bst)) then 'Inner'else 'Leaf' end from bst order by n;

  • marinskiy
     + 4 comments

    Here is Oracle solution from my HackerrankPractice repository:

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

    Feel free to ask if you have any questions :)

  • defiant_dj04
     + 3 comments

    Solution 1: Oracle/MySQL/MS SQL Server

    SELECT n,
	CASE
		WHEN p IS NULL THEN 'Root'
		WHEN n IN (SELECT DISTINCT p FROM bst) THEN 'Inner'
		ELSE 'Leaf'
	END
FROM bst
ORDER BY n;

    Solution 2: Oracle/MySQL/MS SQL Server

    SELECT n,
	CASE
		WHEN p IS NULL THEN 'Root'
		WHEN EXISTS (SELECT * FROM bst in_bst WHERE in_bst.p = out_bst.n) THEN 'Inner'
		ELSE 'Leaf'
	END
FROM bst out_bst
ORDER BY n;

    Solution 3: Oracle/MySQL/MS SQL Server

    SELECT n,
	CASE
		WHEN p IS NULL THEN 'Root'
		WHEN ((SELECT COUNT(*) FROM bst in_bst WHERE in_bst.p = out_bst.n) > 0) THEN 'Inner'
		ELSE 'Leaf'
	END
FROM bst out_bst
ORDER BY n;

    Solution 4: Oracle/MySQL/MS SQL Server

    SELECT n,
	CASE
		WHEN p IS NULL THEN 'Root'
		WHEN n IN (SELECT bst_1.p FROM bst bst_1 JOIN bst bst_2 ON bst_1.p = bst_2.n) THEN 'Inner'
		ELSE 'Leaf'
	END
FROM bst
ORDER BY n;

    Solution 5: MySQL

    SELECT n, IF(p IS NULL, 'Root', IF((SELECT COUNT(*) FROM bst in_bst WHERE in_bst.p = out_bst.n) > 0, 'Inner', 'Leaf')) 
FROM bst out_bst
ORDER BY n;
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