Deque in Data Structure | Double ended queue Data Structure | Stack & Queue using Deque | DSAOne #53 | Summary and Q&A

TL;DR

This video provides an introduction to deque (doubly ended queue) and discusses its implementation, operations, and applications in Java, C++, and HTML.

Key Insights

• 📚 Deque is a data structure that allows add and remove operations from both ends, making it versatile for implementing stack, queue, and doubly ended queue functionalities.
• 🔧 Java's ArrayDeque class implements the Deque interface, which extends the Queue interface and the Collection framework, making it usable as a deque, queue, and collection.
• 📝 Common operations for implementing deque using ArrayDeque in Java include offer first, offer last, add first, add last, get first, get last, remove first, and remove last.
• 📊 ArrayDeque can also be used to implement stack functionalities, such as push, pop, and peek, by utilizing the head pointer and doubling the array size when it gets full.
• 📋 As a queue, ArrayDeque in Java offers operations like offer, poll, and peek, utilizing both head and tail pointers to maintain First In, First Out order.
• 📝 Queue operations in C++ using deque include push back, push front, front, back, pop back, and pop front, allowing elements to be added or removed from both ends.
• ⚙️ Internally, deque in C++ utilizes an array of pointers, but the implementation details are not discussed further in the video.
• 📖 By using ArrayDeque in Java or deque in C++, you can implement various data structures like stack, queue, and doubly ended queue effectively.

Transcript

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Questions & Answers

Q: How is deque implemented in Java using array deque?

In Java, deque is implemented using the array deque class, which combines functionalities of a deque, queue, and collection framework. It allows elements to be added and removed from both ends. The array deque class implements the deque interface, which extends the queue interface, and the queue interface extends the collection framework.

Q: How can array deque be used as a stack in Java?

To use array deque as a stack in Java, you can utilize the push, pop, and peek operations. Push adds an element to the top of the stack, pop removes and returns the topmost element, and peek returns the topmost element without removing it. Internally, array deque uses an array, and the head pointer is used to keep track of the topmost element.

Q: How is deque implemented as a queue in Java using array deque?

In Java, deque can be implemented as a queue using array deque. The offer operation is used to add elements to the tail of the queue, the poll operation removes and returns the element at the head of the queue, and the peek operation returns the element at the head without removing it. Array deque uses both head and tail pointers to manage the queue efficiently.

Q: How is deque implemented in C++ using the HTML library?

In C++, deque can be implemented using the HTML library. The deque in C++ is an array of pointers. The deque provides operations such as push back, push front, pop back, pop front, and functions to get the front and back elements. It allows elements to be added and removed from both ends, making it suitable for various applications.

Summary & Key Takeaways

• The video introduces deque, a data structure that allows elements to be added and removed from both ends.

• It discusses the implementation of deque using array deque in Java, and highlights its functionalities as a queue, stack, and collection framework.

• The video also explains the implementation of deque in C++ using the HTML library, showcasing its operations as a doubly ended queue, stack, and queue.