Homework Help: Questions and Answers: Which of the following statement(s) about stack data structure is/are NOT correct?

a) Top of the Stack always contain the new node b) Stack is the FIFO data structure c) Null link is present in the last node at the bottom of the stack d) Linked List are used for implementing Stacks

Answer:

First, let’s understand about stacks:

Stacks follow the Last-In-First-Out (LIFO) principle.

Elements are added and removed from the same end, called the top.

Stacks can be implemented using arrays or linked lists.

Let’s analyze each statement about the stack data structure one by one to determine which are incorrect.

Given Options: Step by Step Answering

a) Top of the Stack always contains the new node

This is correct. In a stack, when a new element is pushed onto the stack, it is added at the top. Therefore, the top of the stack always contains the most recently added node.

b) Stack is the FIFO data structure

This is incorrect. Stack follows the LIFO (Last In, First Out) principle, not FIFO (First In, First Out). The last element added is the first one to be removed.

c) Null link is present in the last node at the bottom of the stack

This is correct. In a stack implemented using a linked list, the bottom element of the stack does not point to any other node, so its link (next pointer) is indeed null (or None in Python).

d) Linked Lists are used for implementing Stacks

This is correct. A stack can be implemented using various data structures, including linked lists. When implemented using a linked list, the push and pop operations can be performed efficiently.

Final Answer

Based on the above analysis, the only statement that is NOT correct is: