Data Structures: Stacks and Queues

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Questions and Answers

What role does a hash function play in a hash table?

A hash function maps input data to a unique index in the hash table for efficient storage and retrieval.

Explain the concept of collision in hashing and name one resolution technique.

A collision occurs when two different data items map to the same index in a hash table. One resolution technique is separate chaining.

How does separate chaining differ from open addressing in collision resolution?

Separate chaining uses linked lists to handle multiple items at the same index, while open addressing re-hashes to find vacant spaces in the table.

What impact does the uniform distribution of data have on the performance of a hash table?

Uniform distribution minimizes collisions, which enhances the efficiency of search, insert, and delete operations. Signup and view all the answers

In what applications is hashing particularly useful and why?

Hashing is useful in applications like dictionaries and databases due to its quick data retrieval capabilities. Signup and view all the answers

What are the primary operations performed on a stack?

The primary operations performed on a stack are push, pop, peek, and isEmpty. Signup and view all the answers

Explain how the Last-In, First-Out (LIFO) principle works in stacks.

In LIFO, the last element added to the stack is the first one to be removed, meaning the most recently added item is accessed first. Signup and view all the answers

What is a significant disadvantage of array-based stacks?

A significant disadvantage of array-based stacks is the risk of overflow errors when the stack exceeds its fixed capacity. Signup and view all the answers

What is the First-In, First-Out (FIFO) principle in queues?

In FIFO, the first element added to the queue is the first one to be removed, which means items are processed in the order they are received. Signup and view all the answers

Differentiate between enqueue and dequeue operations in queues.

Enqueue adds an element to the rear of the queue, while dequeue removes an element from the front. Signup and view all the answers

How do tries improve string searching compared to other data structures?

Tries allow for efficient prefix matching by organizing strings in a tree structure, enabling quick traversal based on prefix characters. Signup and view all the answers

What is a circular queue and how does it differ from a standard queue?

A circular queue is a variation of an array-based queue that wraps around when reaching the end, improving memory allocation and avoiding overflow issues. Signup and view all the answers

What is the main advantage of using linked list-based stacks over array-based stacks?

The main advantage is that linked list-based stacks do not have a fixed size, preventing overflow issues. Signup and view all the answers

Study Notes

Stacks

Stacks are linear data structures that operate on the Last-In, First-Out (LIFO) principle.
Elements are added and removed from the top of the stack.
Common operations include push (add to top), pop (remove from top), peek (view top element), and isEmpty (check if stack is empty).
Stacks are useful for tasks like function calls, expression evaluation, and undo/redo functionalities.
Stacks can be implemented using arrays or linked lists.
Array-based stacks have a fixed size; overflow errors can occur if the stack exceeds its capacity.
Linked list-based stacks don't have a fixed size but might be slower due to pointer manipulations during push and pop operations.

Queues

Queues are linear data structures that follow the First-In, First-Out (FIFO) principle.
Elements are added to the rear (enqueue) and removed from the front (dequeue).
Common operations include enqueue, dequeue, peek (view front element), and isEmpty (check if queue is empty).
Queues are used for managing tasks (like in a printer queue), handling requests (like in a call center), and implementing breadth-first search algorithms.
Queues can be implemented using arrays or linked lists.
Array-based queues can have overflow problems, while linked list-based queues are size-unrestricted.
Circular queues, a variation of array-based queues, enhance memory use and avoid array copying during enqueue and dequeue operations.

Tries

Tries (Prefix Trees) are tree-based data structures optimized for string searching and prefix matching.
Nodes in the trie represent prefixes of strings. Each node stores pointers to child nodes, representing subsequent characters.
Trie nodes are typically implemented as arrays or linked lists.
Trie nodes can store a single character, or multiple references (if each character needs a separate reference for partial substring matching). This depends on the implementation's needs.
Searching for a string or a prefix in a trie involves traversing the tree using characters and checking for a node marking the end of a word.
Prefix searches only need traversal until the end of the prefix to identify if any words begin with that prefix.
Tries handle large string datasets efficiently due to their efficiency in prefix and complete word matching.

Hashing

Hashing uses hash tables for efficient data storage and retrieval.
A hash function maps data to an index within the hash table.
Hash functions are crucial for generating unique indices based on input data.
Collision resolution handles situations where different data maps to the same index (hash collision).
Common collision resolutions are separate chaining and open addressing.
Separate chaining uses a linked list for elements mapping to the same index; each list node holds data and key. Open addressing re-hashes data until an empty table space is found.
Hashing dramatically improves search, insert, and delete performance compared to other standard data structures.
Hash function effectiveness, distributing data uniformly across the hash table, is critical for minimizing collisions and maximizing performance.
Hashing is vital in dictionaries, databases, caches, and applications demanding speedy data retrieval.

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Description

This quiz covers key concepts of stacks and queues, two fundamental linear data structures. Explore the Last-In, First-Out (LIFO) principle for stacks and the First-In, First-Out (FIFO) principle for queues, including their operations and use cases. Designed for students learning data structures, this quiz will help reinforce your understanding of these essential topics.