What Is a Semaphore | Dataford Interview Questions

Explain what a semaphore is.

Implement a nonblocking counting semaphore simulator that processes task acquire and release operations. Use FIFO ordering for blocked tasks, and record whether each task acquires, blocks, releases, or is awakened.

The function receives an initial permit count and valid operations shaped as { "action": "acquire"|"release", "task": "id" }. Return one event string per operation. A release always belongs to a task currently holding a permit.

Constraints

0 <= initial_permits <= 10^4
1 <= operations.length <= 10^4
Each operation has action equal to "acquire" or "release"
Task identifiers are non-empty strings
A release operation always belongs to a task currently holding a permit
A task appears in at most one waiting or holding state at a time

Function Signature

def simulate_semaphore(initial_permits, operations):

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Problem

Explain what a semaphore is.

Constraints

0 <= initial_permits <= 10^4
1 <= operations.length <= 10^4
Each operation has action equal to "acquire" or "release"
Task identifiers are non-empty strings
A release operation always belongs to a task currently holding a permit
A task appears in at most one waiting or holding state at a time

Function Signature

def simulate_semaphore(initial_permits, operations):

Your question is What Is a Semaphore. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.