In the world of programming, data structures are the building blocks that organize and manage information. Today, we’ll delve into a fundamental structure called a stack. Images a stack of plates, we can only add or remove plates from the top. This “Last-In-First-Out” (LIFO) principle is what defines a stack.
Core Operations of a Stack
- Push: Add an element to the top of the stack.
- Pop: Remove an element from the top and return this element
- Peek: Return the top element without removing it
- isEmpty: Check if the stack is empty
- isFull: Check if the stack is full
Use Cases of Stacks
Stacks are used in various applications, including:
- Function Call Management: Stacks manage function calls and recursion in programming language. Each function call is pushed onto the call stacks and popped when the function returns.
- Undo/Redo Functionality: Many applications use stacks to implement undo/redo features. Each action is push onto stack, allowing users to revert back by popping elements off.
- Backtracking Algorithms: These algorithms explore different path in a problem space. Stacks are used to store the path taken, allowing backtracking when a dead end is reached.
- Expression Evaluation: Stacks are crucial for evaluating mathematical expressions in postfix notation. Operators and operands are pushed onto the stack, and calculations are performed by popping elements according to the expression’s order.
Stack implementation in python
class Stack:
def __init__(self):
self.items = []
def push(self, item):
self.items.append(item)
def pop(self):
if self.is_empty():
raise IndexError("Pop from an empty stack")
return self.items.pop()
def peek(self):
if self.is_empty():
raise IndexError("Peek from an empty stack")
return self.items[-1]
def is_empty(self):
return len(self.items) == 0
def size(self):
return len(self.items)
def __str__(self):
return str(self.items)
Source Code: https://github.com/hongquan080799/data-structure-and-algorithms
Conclusion
Stacks are a fundamental data structure with a variety of practical applications. Understanding how to implement and use a stack is essential for tackling many algorithmic problems and for efficient programming. Whether you’re managing function calls, evaluating expressions, or implementing an undo mechanism, stacks provide a robust solution with their simple yet powerful LIFO principle.
