Implement Memory Allocation and In-Memory Records

Problem Statement

You are tasked with building an in-memory management system that handles both raw byte allocation and user record storage.

Part 1: Memory Allocator

You have a fixed-size byte array of capacity N. Implement a memory allocator using the first-fit strategy. You must support:

• allocate(size): Find the first available block of size bytes. Return the start index, or -1 if unavailable.
• free(index): Release the block starting at index. You must merge contiguous free blocks to prevent fragmentation.

Part 2: User Records

Use your allocator (or a simulated approach) to store user records. Each record contains ID, Name (max 32 bytes), and ManagerID. Records are stored in a flat array, but their relationships form a tree.

• add_record(id, name, manager_id): Store a new record.
• get_subordinates(manager_id): Return a list of all names that report directly or indirectly to the given manager_id.

Constraints

• N (total bytes) <= 10,000.
• Number of records <= 100.
• ID and ManagerID are integers.

Example

// Allocate 10 bytes at index 0
// Free index 0
// Add user: ID 1, Name "Alice", ManagerID 0
// Add user: ID 2, Name "Bob", ManagerID 1
// get_subordinates(1) -> ["Bob"]

Edge Cases

• Allocating more than the remaining contiguous block size.
• Freeing an index that was never allocated.
• Handling the root user (ManagerID = 0) in the hierarchy.