[SQL] 해커랭크 Binary Tree Nodes

SELECT G.NODE
  FROM (
         SELECT CONCAT(N, ' Root') AS NODE
              , N
           FROM BST
          WHERE P IS NULL
      UNION ALL
         SELECT CONCAT(N, ' Inner') AS NODE
              , N
           FROM BST
          WHERE N IN (
                       SELECT P
                         FROM BST
                     )
            AND P IS NOT NULL
      UNION ALL       
         SELECT CONCAT(N, ' Leaf') AS NODE
              , N
           FROM BST
          WHERE N NOT IN (
                           SELECT DISTINCT P
                             FROM BST
                            WHERE P IS NOT NULL
                         )
       ) G
ORDER BY G.N

 

 

 

해커랭크 Binary Tree Nodes SQL