Define Data Structure
A data structure is a way of organizing and storing data in a computer so that it can be accessed and used efficiently. It defines the way data is arranged, stored, and manipulated, and includes various types such as arrays, linked lists, stacks, queues, trees, and graphs.
What is ADT
ADT stands for Abstract Data Type. It is a high-level description of a data structure that specifies the behavior and operations that can be performed on the data, without specifying the implementation details. ADTs provide a way of abstracting the data structure's properties, allowing the programmer to focus on the problem at hand rather than the underlying implementation. Examples of ADTs include stacks, queues, lists, and trees.
Explain Stack and Queue
A stack is a data structure that follows the Last-In-First-Out (LIFO) principle. It is like a stack of plates, where the last plate placed on top of the stack is the first one to be removed. Elements are added and removed from the same end, called the top of the stack. Common operations include push (add element to the top) and pop (remove the top element).
A queue is a data structure that follows the First-In-First-Out (FIFO) principle. It is like a queue of people waiting in line, where the first person to join the queue is the first one to be served. Elements are added at one end, called the rear of the queue, and removed from the other end, called the front of the queue. Common operations include enqueue (add element to the rear) and dequeue (remove the front element).
Explain Stack Operations with example
Stacks support two main operations, namely push and pop, which are used to add and remove elements from the stack, respectively.
1. Push: The push operation adds an element to the top of the stack. This is done by incrementing the stack pointer and placing the new element in the position pointed to by the stack pointer.
For example, let's consider a stack of integers with a capacity of 5. Initially, the stack is empty, and the stack pointer points to the first position in the stack (index 0). When we push the value 10 onto the stack, the stack pointer is incremented to 1, and the value 10 is placed in the first position of the stack. Similarly, if we push the values 20, 30, 40, and 50 onto the stack, the stack will look like this:
Top of stack (index 4) -> 50
40
30
20
Bottom of stack (index 0) -> 10
2. Pop: The pop operation removes the element from the top of the stack. This is done by decrementing the stack pointer and returning the value at the position pointed to by the stack pointer.
Continuing with our previous example, if we pop an element from the stack, the value 50 is removed from the top of the stack, the stack pointer is decremented to 3, and the value 40 becomes the new top of the stack. If we pop another element, the value 40 is removed, the stack pointer is decremented to 2, and the value 30 becomes the new top of the stack. The stack now looks like this:
Top of stack (index 2) -> 30
20
Bottom of stack (index 0) -> 10
It's important to note that popping from an empty stack is an error, and it's also possible to implement additional operations such as peek (to get the value of the top element without removing it) and isEmpty (to check if the stack is empty).
Explain Queue Operations with example
Queues support two main operations, namely enqueue and dequeue, which are used to add and remove elements from the queue, respectively.
1. Enqueue: The enqueue operation adds an element to the rear of the queue. This is done by inserting the new element at the end of the queue and updating the rear pointer to point to the new end of the queue.
For example, let's consider a queue of characters with a capacity of 5. Initially, the queue is empty, and both the front and rear pointers point to the first position in the queue (index 0). When we enqueue the character 'A' onto the queue, the character is inserted at the rear of the queue, and the rear pointer is incremented to 1. Similarly, if we enqueue the characters 'B', 'C', 'D', and 'E' onto the queue, the queue will look like this:
Front of queue (index 0) -> A
B
C
D
Rear of queue (index 4) -> E
2. Dequeue: The dequeue operation removes the element from the front of the queue. This is done by returning the value at the position pointed to by the front pointer and updating the front pointer to point to the next element in the queue.
Continuing with our previous example, if we dequeue an element from the queue, the character 'A' is removed from the front of the queue, the front pointer is incremented to 1, and the character 'B' becomes the new front of the queue. If we dequeue another element, the character 'B' is removed, the front pointer is incremented to 2, and the character 'C' becomes the new front of the queue. The queue now looks like this:
Front of queue (index 2) -> C
D
Rear of queue (index 4) -> E
It's important to note that dequeuing from an empty queue is an error, and it's also possible to implement additional operations such as peek (to get the value of the front element without removing it) and isEmpty (to check if the queue is empty).
Tags
Data Structure