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Implement a Fixed-Capacity Deque

Last updated: May 2, 2026

Quick Overview

This question evaluates proficiency with double-ended queue semantics, fixed-capacity data structure design, constant-time (O(1)) operations, and correct handling of boundary conditions and wraparound.

  • medium
  • Applied
  • Coding & Algorithms
  • Machine Learning Engineer

Implement a Fixed-Capacity Deque

Company: Applied

Role: Machine Learning Engineer

Category: Coding & Algorithms

Difficulty: medium

Interview Round: Technical Screen

Design and implement a fixed-capacity double-ended queue. The data structure is initialized with an integer capacity `k` and must support the following operations in `O(1)` time: - `insertFront(value)`: Insert `value` at the front. Return `true` if successful, or `false` if the deque is full. - `insertLast(value)`: Insert `value` at the back. Return `true` if successful, or `false` if the deque is full. - `deleteFront()`: Delete the front element. Return `true` if successful, or `false` if the deque is empty. - `deleteLast()`: Delete the back element. Return `true` if successful, or `false` if the deque is empty. - `getFront()`: Return the front element, or `-1` if the deque is empty. - `getRear()`: Return the back element, or `-1` if the deque is empty. - `isEmpty()`: Return whether the deque is empty. - `isFull()`: Return whether the deque is full. You may assume `1 <= k <= 1000` and values are integers. Explain your representation and handle wraparound correctly.

Quick Answer: This question evaluates proficiency with double-ended queue semantics, fixed-capacity data structure design, constant-time (O(1)) operations, and correct handling of boundary conditions and wraparound.

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Applied
Apr 14, 2026, 12:00 AM
Machine Learning Engineer
Technical Screen
Coding & Algorithms
0
0

Design and implement a fixed-capacity double-ended queue.

The data structure is initialized with an integer capacity k and must support the following operations in O(1) time:

  • insertFront(value) : Insert value at the front. Return true if successful, or false if the deque is full.
  • insertLast(value) : Insert value at the back. Return true if successful, or false if the deque is full.
  • deleteFront() : Delete the front element. Return true if successful, or false if the deque is empty.
  • deleteLast() : Delete the back element. Return true if successful, or false if the deque is empty.
  • getFront() : Return the front element, or -1 if the deque is empty.
  • getRear() : Return the back element, or -1 if the deque is empty.
  • isEmpty() : Return whether the deque is empty.
  • isFull() : Return whether the deque is full.

You may assume 1 <= k <= 1000 and values are integers. Explain your representation and handle wraparound correctly.

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