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IshaSQL

Foundations Track · Medium · 25 min

Tree Node

Table: Tree +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | p_id | int | +-------------+------+ id is the column with uni...

Foundations Track
Medium
25 min
aggregation
filtering

Company labels are directional practice context, not official interview guidance.

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Objective

Practice aggregation through a IshaSQL-tagged business scenario.

Approach

Use this track to lock in clean query structure, basic filtering logic, and confidence with grouped output.

Company context

Company labels are directional practice context, not official interview guidance.

Prereq: query basics
Prereq: filtering

Table: Tree +-------------+------+ | Column Name | Type | +-------------+------+ | id | int | | p_id | int | +-------------+------+ id is the column with unique values for this table. Each row of this table contains information about the id of a node and the id of its parent node in a tree. The given structure is always a valid tree. Each node in the tree can be one of three types: "Leaf" : if the node is a leaf node. "Root" : if the node is the root of the tree. "Inner" : If the node is neither a leaf node nor a root node. Write a solution to report the type of each node in the tree. Return the result table in any order . The result format is in the following example. Example 1: Input: Tree table: +----+------+ | id | p_id | +----+------+ | 1 | null | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 2 | +----+------+ Output: +----+-------+ | id | type | +----+-------+ | 1 | Root | | 2 | Inner | | 3 | Leaf | | 4 | Leaf | | 5 | Leaf | +----+-------+ Explanation: Node 1 is the root node because its parent node is null and it has child nodes 2 and 3. Node 2 is an inner node because it has parent node 1 and child node 4 and 5. Nodes 3, 4, and 5 are leaf nodes because they have parent nodes and they do not have child nodes. Example 2: Input: Tree table: +----+------+ | id | p_id | +----+------+ | 1 | null | +----+------+ Output: +----+-------+ | id | type | +----+-------+ | 1 | Root | +----+-------+ Explanation: If there is only one node on the tree, you only need to output its root attributes. Note: This question is the same as 3054: Binary Tree Nodes.

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