Linked list based implementation of Stack ADT | Data structures | SNS Institutions

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Linked List Based Implementation of Stack ADT

A stack is a linear data structure that works on the Last In First Out (LIFO) principle. In the linked list-based implementation, a stack is represented using a singly linked list, where each node consists of two parts:

1. Data field – stores the actual element.


2. Pointer field – stores the address of the next node.



A pointer called top always points to the node that was most recently inserted into the stack. Initially, when the stack is empty, top = NULL.

Operations:

Push (Insert): A new node is created and inserted at the beginning of the linked list. The top pointer is updated to this new node.

Pop (Delete): The node pointed by top is removed. The top pointer is updated to the next node in the list. If top = NULL, the stack is empty (underflow).

Peek (Top): Returns the data stored in the node pointed by top without removing it.


Advantages:

The stack size is not fixed; it can grow or shrink dynamically as memory is allocated or freed during runtime.

No memory is wasted since elements are created only when needed.


Limitations:

Each node requires extra memory for the pointer field, causing overhead compared to array implementation.

Accessing elements other than the top is not efficient.


Conclusion:
The linked list-based implementation of a stack is flexible and avoids the problem of overflow (unless memory is exhausted). It is preferred when the maximum stack size is not known in advance.