Design Circular Deque

Design Circular Deque is a Medium Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Design Patterns pattern, in the Design (General/Specific) subpattern.

Problem statement

Design your implementation of the circular double-ended queue (deque).

Implement the MyCircularDeque class:

- MyCircularDeque(int k) Initializes the deque with a maximum size of k.

- boolean insertFront() Adds an item at the front of Deque. Returns true if the operation is successful, or false otherwise.

- boolean insertLast() Adds an item at the rear of Deque. Returns true if the operation is successful, or false otherwise.

- boolean deleteFront() Deletes an item from the front of Deque. Returns true if the operation is successful, or false otherwise.

- boolean deleteLast() Deletes an item from the rear of Deque. Returns true if the operation is successful, or false otherwise.

- int getFront() Returns the front item from the Deque. Returns -1 if the deque is empty.

- int getRear() Returns the last item from Deque. Returns -1 if the deque is empty.

- boolean isEmpty() Returns true if the deque is empty, or false otherwise.

- boolean isFull() Returns true if the deque is full, or false otherwise.

Example 1:

Input ["MyCircularDeque", "insertLast", "insertLast", "insertFront", "insertFront", "getRear", "isFull", "deleteLast", "insertFront", "getFront"] [[3], [1], [2], [3], [4], [], [], [], [4], []] Output [null, true, true, true, false, 2, true, true, true, 4]

Explanation MyCircularDeque myCircularDeque = new MyCircularDeque(3); myCircularDeque.insertLast(1); // return True myCircularDeque.insertLast(2); // return True myCircularDeque.insertFront(3); // return True myCircularDeque.insertFront(4); // return False, the queue is full. myCircularDeque.getRear(); // return 2 myCircularDeque.isFull(); // return True myCircularDeque.deleteLast(); // return True myCircularDeque.insertFront(4); // return True myCircularDeque.getFront(); // return 4

Constraints:

- 1 <= k <= 1000

- 0 <= value <= 1000

- At most 2000 calls will be made to insertFront, insertLast, deleteFront, deleteLast, getFront, getRear, isEmpty, isFull.

Topics and companies

Topics: Array, Linked List, Design, Queue.

Reported in interviews at Amazon.

How to practise Design Circular Deque on Thita.ai

Starter code is provided in C, C#, C++, Go, Java, JavaScript and Python. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(1) for all operations. Each operation (insertFront, insertLast, deleteFront, deleteLast, getFront, getRear, isEmpty, isFull) only involves a constant number of arithmetic and array access operations. time and O(k), where k is the maximum size of the deque. The space is used for the internal buffer of size k+1 to distinguish full and empty states. space.

Open Design Circular Deque in the code editor, or read the Design Circular Deque editorial for a worked solution with its approach and complexity analysis.

Where Design Circular Deque sits in the DSA pattern sheet

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