How should I practice Bounded Service Instance Registry?

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

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Bounded Service Instance Registry

Revolut● EasyNEW GRADPHONE SCREEN

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Problem statement

Implement the registration behavior for an in-memory service-instance registry. Process the attempted instance addresses from left to right and return one outcome for each attempt.

Return REGISTERED and store an address when it is new and fewer than 10 unique addresses are stored.
Return DUPLICATE when the address is already stored, including when the registry is full.
Return FULL when the address is new but 10 unique addresses are already stored.

Each result models one atomic register call. In a shared concurrent implementation, the duplicate check, capacity check, and insertion must occur in one critical section.

Function

registerInstances(addresses: String[]) → String[]

Examples

Example 1

addresses = ["192.168.1.1","192.168.1.2","192.168.1.1"]return = ["REGISTERED","REGISTERED","DUPLICATE"]

The repeated address is rejected without consuming capacity.

Example 2

addresses = ["a","b","c","d","e","f","g","h","i","j","k"]return = ["REGISTERED","REGISTERED","REGISTERED","REGISTERED","REGISTERED","REGISTERED","REGISTERED","REGISTERED","REGISTERED","REGISTERED","FULL"]

After ten unique registrations, an eleventh unique address is rejected.

Constraints

0 <= addresses.length <= 100000.
Every address has length from 1 to 100.
Addresses are case-sensitive opaque strings.

Source note: The source image is a source-neutral excerpt of the author-reported prompt.