Stack Data Structure

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Questions and Answers

What is the fundamental principle that guides the operation of a stack data structure?

LIFO (Last In, First Out)

What are the two common implementation methods for a stack data structure?

Arrays and linked lists

What happens when a stack exceeds its maximum capacity?

A stack overflow occurs

What is the effect of the push operation on the size of the stack?

It increases the size of the stack by 1 Signup and view all the answers

What is the time complexity of the push and pop operations in both array and linked list implementations?

O(1) Signup and view all the answers

What is the space complexity of an array implementation of a stack?

O(n), where n is the maximum capacity of the stack Signup and view all the answers

How does the pop operation affect the top pointer or index of the stack?

It updates the top pointer or index Signup and view all the answers

What is the significance of the top pointer or index in a stack implementation?

It indicates the top of the stack Signup and view all the answers

What is the primary advantage of using a FIFO method in a queue data structure?

It ensures that the elements are processed in the order they were received, which is essential in many applications such as job scheduling and print queues. Signup and view all the answers

How does the LIFO method differ from the FIFO method in a queue data structure?

In LIFO, the last element added to the queue is the first one to be removed, whereas in FIFO, the first element added is the first one to be removed. Signup and view all the answers

What is the purpose of the peek operation in a queue data structure?

To return the front element of the queue without removing it, allowing inspection of the next element to be removed. Signup and view all the answers

What is the consequence of removing the front element from a queue using the dequeue operation?

The element that was added first is removed first, and the next element in the queue becomes the new front element. Signup and view all the answers

What is the purpose of the size operation in a queue data structure?

To return the number of elements in the queue, used to check if the queue is empty or full. Signup and view all the answers

What is the significance of the isEmpty operation in a queue data structure?

It checks if the queue has no elements, returning true if the queue is empty and false otherwise. Signup and view all the answers

Study Notes

Data Structure

A stack is a linear data structure that follows the LIFO (Last In, First Out) principle.
It consists of a collection of elements, with each element added and removed from the top of the stack.
Elements can be added (pushed) or removed (popped) from the top of the stack only.

Implementation

Stacks can be implemented using arrays or linked lists.
Array implementation:
- Uses a fixed-size array to store elements.
- The top of the stack is indicated by a pointer or index.
Linked list implementation:
- Each element is a node with a reference to the next node.
- The top of the stack is indicated by a pointer to the top node.

Stack Overflow

A stack overflow occurs when the stack exceeds its maximum capacity.
This can happen when the stack is implemented using an array and the array is full.
Stack overflow can lead to program crashes or errors.

Push and Pop Operations

Push: adds an element to the top of the stack.
- Increases the size of the stack by 1.
- Updates the top pointer or index.
Pop: removes the top element from the stack.
- Decreases the size of the stack by 1.
- Updates the top pointer or index.

Algorithm Analysis

Time complexity:
- Push and pop operations have a time complexity of O(1) in both array and linked list implementations.
- This is because the operations only affect the top element of the stack.
Space complexity:
- Array implementation has a space complexity of O(n), where n is the maximum capacity of the stack.
- Linked list implementation has a space complexity of O(n), where n is the number of elements in the stack.

Data Structure

A stack is a linear data structure that follows the LIFO (Last In, First Out) principle.
Elements in a stack are added and removed from the top only.

Implementation

Stacks can be implemented using either arrays or linked lists.
Array implementation uses a fixed-size array with a pointer or index to indicate the top of the stack.
Linked list implementation uses nodes with references to the next node, with a pointer to the top node.

Stack Overflow

A stack overflow occurs when the stack exceeds its maximum capacity.
This can happen when the stack is implemented using an array and the array is full.
Stack overflow can lead to program crashes or errors.

Push and Pop Operations

The push operation adds an element to the top of the stack, increasing the stack size by 1, and updating the top pointer or index.
The pop operation removes the top element from the stack, decreasing the stack size by 1, and updating the top pointer or index.

Algorithm Analysis

Push and pop operations have a time complexity of O(1) in both array and linked list implementations.
Array implementation has a space complexity of O(n), where n is the maximum capacity of the stack.
Linked list implementation has a space complexity of O(n), where n is the number of elements in the stack.

Queue Data Structure

A queue is a FIFO (First-In-First-Out) data structure, meaning that the order of operations follows a specific sequence.
Queues are collections of elements that are added and removed in a specific order.
Queues are commonly used in various applications, including job scheduling, print queues, and network protocols.

FIFO (First-In-First-Out)

FIFO is a method of processing items in the order they were received.
The first item added to the queue is the first one to be removed.
FIFO is the most widely used implementation of a queue.

Queue Operations

Adding and Removing Elements

Enqueue (Add): adds an element to the end of the queue, making it the last element.
Dequeue (Remove): removes the front element from the queue, which is the first element added.

Inspecting the Queue

Peek (Front): returns the front element of the queue without removing it, allowing inspection of the next element to be removed.
Size: returns the number of elements in the queue, useful for checking if the queue is empty or full.

Checking Queue Status

IsEmpty: checks if the queue is empty, returning true if it has no elements, and false otherwise.
IsFull: checks if the queue is full, returning true if it has reached its maximum capacity, and false otherwise.