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This is a medium difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Tml.

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This question is commonly asked for Software Engineer candidates at Tml during technical interviews.

Implement a Resizable Deque | Tml Interview Question

Q: Implement a Resizable Deque

This question evaluates proficiency in data structures and array-based implementations, specifically building a resizable double-ended queue (deque) backed by a circular array and understanding amortized O(1) operation costs.

Implement a double-ended queue (deque) data structure backed by a circular array.

Your deque should support insertion and removal from both ends and should automatically resize when it becomes full.

Required operations:

pushFront(value) : Insert value at the front.
pushBack(value) : Insert value at the back.
popFront() : Remove and return the front element. If the deque is empty, handle the error clearly.
popBack() : Remove and return the back element. If the deque is empty, handle the error clearly.
peekFront() : Return the front element without removing it.
peekBack() : Return the back element without removing it.
isEmpty() : Return whether the deque is empty.
size() : Return the number of elements currently stored.

Implementation requirements:

Use an array as the underlying storage.
Treat the array as circular so that operations at both ends are efficient.
When the array is full, allocate a larger array, copy the elements in logical deque order, and update internal pointers correctly.
Each operation should run in O(1) amortized time.