Custom Stack or Queue | Dataford Interview Questions

How would you implement a custom stack or queue using basic arrays or linked lists?

Implement process_operations(mode, operations), where mode is either "stack" or "queue". Each operation is an array such as ["push", value], ["pop"], ["enqueue", value], or ["dequeue"]. Return the values produced by removal and peek operations in order. Return None for removal or peek operations on an empty structure.

Use a custom implementation rather than the built-in queue classes. The structure should support constant-time insertion, removal, and peek operations.

Constraints

mode is either "stack" or "queue"
1 <= operations.length <= 10^4
Each operation is valid for the selected mode
Values may be integers, strings, or null
An empty pop, dequeue, or peek returns None

Function Signature

def process_operations(mode, operations):

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Problem

How would you implement a custom stack or queue using basic arrays or linked lists?

Use a custom implementation rather than the built-in queue classes. The structure should support constant-time insertion, removal, and peek operations.

Constraints

mode is either "stack" or "queue"
1 <= operations.length <= 10^4
Each operation is valid for the selected mode
Values may be integers, strings, or null
An empty pop, dequeue, or peek returns None

Function Signature

def process_operations(mode, operations):

Your question is Custom Stack or Queue. 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.