How should I practice Aggregate Machine Topology?

Start by reading the full statement, solve the visible examples, then compare the pattern against related OpenAI phone screen problems in FastPrep.

Is Aggregate Machine Topology associated with OpenAI?

FastPrep tags this as a OpenAI phone screen coding practice problem when the problem catalog has that company and stage context.

Aggregate Machine Topology

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Problem statement

A cluster snapshot contains one report from every machine. For each index i, machineIds[i] is a unique machine ID and parentIds[i] is the parent machine's ID. Exactly one machine has parent -1; it is the root. The remaining parent relationships form one rooted tree.

Return a canonical topology summary. Each output row is [machineId, parentId, depth, subtreeSize], where depth counts edges from the root and subtreeSize counts the machine itself and every descendant.

Rows must use preorder traversal. When a machine has multiple children, visit them in increasing machine-ID order. The root row therefore exposes the total machine count in its subtreeSize field.

Function

aggregateMachineTopology(machineIds: int[], parentIds: int[]) → int[][]

Examples

Example 1

machineIds = [30,10,20]parentIds = [10,-1,10]return = [[10,-1,0,3],[20,10,1,1],[30,10,1,1]]

Machine 10 is the root. Its children are visited as 20 and then 30. The root subtree contains all three machines.

Example 2

machineIds = [7,2,9,1,5,3]parentIds = [3,1,3,-1,2,1]return = [[1,-1,0,6],[2,1,1,2],[5,2,2,1],[3,1,1,3],[7,3,2,1],[9,3,2,1]]

The root has children 2 and 3. Machine 2 owns a two-machine subtree, while machine 3 owns a three-machine subtree. Preorder visits each parent's increasing-ID children before returning to later siblings.

Constraints

1 <= machineIds.length == parentIds.length <= 100000.
Every machine ID is unique and lies in [0, 10^9].
Exactly one value in parentIds is -1.
Every other parent ID occurs in machineIds, and all parent relationships form one rooted tree.
The output rows use deterministic preorder with children sorted by increasing machine ID.