What Is Stack in Data Structure Simple Definition?
A stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle. It is a container of objects that allows operations such as adding an element to the top (push) and removing an element from the top (pop). The element added last will be the first one to be removed.
Key Features of a Stack:
- It operates on a restricted set of operations: push and pop.
- Elements can only be inserted or removed at one end, known as the top of the stack.
- The most recently added element is always at the top, while the oldest element is at the bottom.
The push operation adds an element to the top of the stack. It increases the size of the stack by one and places the new element in its appropriate position.
The pop operation removes an element from the top of the stack. It decreases the size of the stack by one and returns the removed element. The next element below it becomes the new top.
Let’s consider a simple example to understand how a stack works:
- Create an empty stack.
- Push elements “A”, “B”, and “C” onto the stack in that order.
- The stack now contains three elements: “C” at the top, followed by “B”, and then “A” at the bottom. The size of the stack is three.
- Perform the pop operation. The top element “C” is removed, and the stack size becomes two.
- The new top of the stack is “B”.
Applications of Stacks:
Stacks are widely used in computer science and software development due to their simplicity and efficiency. Some common applications include:
- Function call management: Stacks are used to store function calls and return addresses during program execution.
- Expression evaluation: Stacks can be used to evaluate arithmetic expressions, including infix, postfix, and prefix notations.
- Undo/Redo functionality: Stacks can be used to implement undo/redo operations in applications.
- Backtracking: Stacks are useful for backtracking algorithms that require storing the state at each step.
A stack is a fundamental data structure that follows the LIFO principle. It allows efficient insertion and removal of elements from one end.
Understanding stacks is crucial for solving various algorithmic problems and implementing efficient solutions in software development. Remember to always consider the LIFO principle when working with stacks!