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HomeBlogWeb DevelopmentWhat is Stack Data Structure? Types, Operations, Implementation
In the field of computer science and programming, whether it's managing data, executing algorithms, or optimizing memory usage, I always required streamlined processes. The stack data structure is a fundamental tool that embodies simplicity and efficiency in data management.
Imagine you are in a cafeteria, delicately stacking plates one on top of the other after each use. As you finish each plate, you place it at the top of the stack. When it's time to clean up, you instinctively start with the top plates and work your way down. This straightforward approach reflects the essence of a stack data structure, which operates on the Last In, First Out (LIFO) principle.
In this article, I will walk you through the stack definition in data structure, including its implementation, operations of stack in data structure, and applications in various domains. I will deep-dive into how stacks are used in algorithmic problem solving and memory management. Understanding the nuances of stacks allows us programmers to use this powerful data structure to write efficient, refined, and error-resistant code. Unlock the power of problem-solving with KnowledgeHut’s Data Structures course subjects Using Java' – Enroll now to elevate your coding skills!
Definition: A stack is a linear data structure that operates on the Last In, First Out (LIFO) principle, which means that the last element added to the stack is the first to be deleted/removed.
Operations: It has two main operations: push, that adds an element to the very top of the stack, and pop, which removes/deletes the top element.
Implementation: Stacks can be implemented using different data structures like arrays or linked lists, with arrays delivering constant-time access but limited capacity and linked lists providing variable allocation of memory but slower access.
Applications: Stacks are commonly used in software applications to manage function calls, evaluate expressions, parse data, and implement undo mechanisms.
Basic Features of Stack
A stack data structure functions based on its core operations and principles:
A stack is either initialized as an empty data structure or with a predetermined capacity if implemented as an array.
Stacks can differ in their implementation and usage, resulting in various types tailored to specific applications. Here are some common stacks:
Priority stacks prioritize certain elements over others according to predefined criteria. Elements with a higher priority are placed near the top of the stack data structure and thus accessed earliest during pop operations.
The following Python functions demonstrate how to perform basic stack operations. You can use them to manipulate stacks in your Python code.
1.Push Operation: Pushing an element onto the top of the stack data structure.
def push(stack, element): stack.append(element)
2.Pop Operation: Removing/Deleting the top element from the stack data structure.
def pop(stack): if not stack: return "Stack is empty" else: return stack.pop()
3.Peek Operation: Viewing the topmost element of the stack data structure without removing it.
def peek(stack): if not stack: return "Stack is empty" else: return stack[-1]
The implementation of a stack data structure in Python is as follows:
class Stack: def __init__(self): # Initialize an empty stack self.stack = [] def push(self, element): # Pushes an element onto the top of the stack self.stack.append(element) def pop(self): # Removes and returns the top element from the stack if not self.is_empty(): return self.stack.pop() else: return "Stack is empty" def peek(self): # Returns the top element of the stack without removing it if not self.is_empty(): return self.stack[-1] else: return "Stack is empty" def is_empty(self): # Checks if the stack is empty return len(self.stack) == 0 def size(self): # Returns the number of elements in the stack return len(self.stack)
You can create a new stack object and use these methods to manipulate it as needed in your Python code. For example:
stack = Stack()
stack.push(5)
stack.push(8)
stack.push(15)
print("Size of stack:", stack.size())# Output: 3
print("Top element of stack:", stack.peek())# Output: 15
print("Popped element:", stack.pop())# Output: 12
print("Size of stack after popping:", stack.size())# Output: 2
Let's look at a simple problem that involves determining the balance of parentheses, brackets, and braces in a given string. This problem is a classic example of using a stack data structure to effectively assess whether symbols are correctly nested.
Question: You are given a string consisting of parentheses, brackets, and braces. Determine whether the string is balanced, meaning that each opening symbol has a corresponding closing symbol, and they are properly nested.
Example:
Input: "(([]))" Output: True
Input: "{[()]}" Output: True
Input: "{[))" Output: False
Solution:
def checkBalanced(s): # takes a string as an parameter
stack = [] # Initializing a empty stack
mapping = {')': '(', ']': '[', '}': '{'}
for char in s:
if char in mapping.values():
stack.append(char)
elif char in mapping.keys():
if not stack or mapping[char] != stack.pop():
return False
else:
# Ignore characters other than parentheses, brackets, and braces
continue
return len(stack) == 0
# Test the function
print(checkBalanced("(([]))"))# Output: True
print(checkBalanced("{[()]}"))# Output: True
print(checkBalanced("{[))"))# Output: False
Explanation:
In this comprehensive article, I delved into the world of stack data structure, discovering their fundamental principles, operations, implementations, and real-life applications of stack data structure. As I progressed, we learned about the importance of stack data structure in computer science and programming by investigating their versatility in problem-solving, memory management, and algorithmic efficiency, as well as their Last In, First Out (LIFO) properties. We've seen how stack operations like push, pop, and peek, as well as their Python implementation, can be used to manage data and execute algorithms in an efficient and intuitive manner. In addition, I made you look at practical application of stack in function call management, expression evaluation, syntax parsing, undo mechanisms, and more.
Stack data structure plays an important role in software development, providing simple yet powerful solutions to complicated problems. Programmers who understand the concepts and application of stack can improve their problem-solving abilities and create efficient, elegant, and robust software systems. Thus, stacks serve as pillar of computational efficiency, enabling us to create innovative solutions while navigating the complexities of modern computing. Transform into a Full-Stack expert and secure your dream job as a Software Engineer with KnowledgeHut's Software Engineer certificate programs online.
In programming languages such as Python and Java, I initialize an empty data structure with arrays or linked lists to create a stack. I can also define additional stack manipulation methods, such as peek, which shows the top element without removing it, and isEmpty, which checks whether the stack is empty. This serves as a foundation to carry out various stack operations and enables efficient data management in my programs.
Stack algorithms use stack data structure to solve problems efficiently across multiple domains. These algorithms frequently use the stack's Last In, First Out (LIFO) property to simplify processes such as function call management, expression evaluation, parsing, and backtracking.
When attempting to pop from an empty stack, an underflow error is typically returned, indicating that the stack is empty, and the operation cannot be completed. Furthermore, some of the stack example may include methods such as is Empty that check the stack's status before attempting a pop operation, resulting in safer and more robust code execution.
The top element, also known as the peek element, is the stack's latest addition. It represents the next element to be utilized or removed, allowing for more efficient data manipulation. This element is critical in stack data structure algorithm that make choices based on the stack's current state, such as when evaluating expressions or managing function calls.
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