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Basics & Data Structures

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Array Access

array[0..5]indexed access

Array

Stack

Queue

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Sorting

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Graphs

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Beginner Friendly

Stack: Array Implementation

Explore LIFO (Last In, First Out) through push, pop, and peek. Watch how the top pointer moves as elements enter and leave.

Interactive Operations

Array Implementation

O(1) Operations

Stack Visualization

Elements are added/removed from the TOP only — LIFO principle.

Color Legend

DefaultActive / ScanningCompletedError

Speed:

Max Size:

[0]

[1]

[2]

[3]

[4]

[5]

[6]

[7]

0 / 8

Size / Capacity

Empty

Status

Current Step

Use Push, Pop, or Peek to begin visualization.

Complexity Analysis

O(1)

Push

O(1)

Pop

O(1)

Peek

O(n) Space

Fixed array allocation

Stack Operations

Push

Add element to the top — increment top pointer, assign value

Pop

Remove and return top element — decrement top pointer

Peek / Top

Read top element without removing it

Real-World Applications

Function Call Stack

OS manages function calls using a call stack

Undo Operations

Ctrl+Z pushes state; undo pops it

Expression Evaluation

Parsing parentheses and arithmetic operators

Browser History

Back button pops the last visited page

Syntax Checking

Matching brackets, braces, and parentheses

Test Yourself

Q1/3

What does LIFO stand for?

Implementation

Python

class StackArray:
    def __init__(self, max_size):
        self.array = [None] * max_size  # Fixed-size array
        self.top = -1                   # Index of top element
        self.max_size = max_size

    def push(self, value):
        if self.top >= self.max_size - 1:
            raise Exception("Stack Overflow")
        self.top += 1
        self.array[self.top] = value
        return value

    def pop(self):
        if self.top < 0:
            raise Exception("Stack Underflow")
        value = self.array[self.top]
        self.array[self.top] = None
        self.top -= 1
        return value

    def peek(self):
        if self.top < 0:
            raise Exception("Stack is Empty")
        return self.array[self.top]

    def is_empty(self):
        return self.top < 0

    def is_full(self):
        return self.top >= self.max_size - 1

    def size(self):
        return self.top + 1

DSAverse

Basics & Data Structures

Loading Data Structures...

Array Access

array[0..5]indexed access

Array

Stack

Queue

Back to Basics

Beginner Friendly

Stack: Array Implementation

Explore LIFO (Last In, First Out) through push, pop, and peek. Watch how the top pointer moves as elements enter and leave.

Interactive Operations

Array Implementation

O(1) Operations

Stack Visualization

Elements are added/removed from the TOP only — LIFO principle.

Color Legend

DefaultActive / ScanningCompletedError

Speed:

Max Size:

[0]

[1]

[2]

[3]

[4]

[5]

[6]

[7]

0 / 8

Size / Capacity

Empty

Status

Current Step

Use Push, Pop, or Peek to begin visualization.

Complexity Analysis

O(1)

Push

O(1)

Pop

O(1)

Peek

O(n) Space

Fixed array allocation

Stack Operations

Push

Add element to the top — increment top pointer, assign value

Pop

Remove and return top element — decrement top pointer

Peek / Top

Read top element without removing it

Real-World Applications

Function Call Stack

OS manages function calls using a call stack

Undo Operations

Ctrl+Z pushes state; undo pops it

Expression Evaluation

Parsing parentheses and arithmetic operators

Browser History

Back button pops the last visited page

Syntax Checking

Matching brackets, braces, and parentheses

Test Yourself

Q1/3

What does LIFO stand for?

Implementation

Python

class StackArray:
    def __init__(self, max_size):
        self.array = [None] * max_size  # Fixed-size array
        self.top = -1                   # Index of top element
        self.max_size = max_size

    def push(self, value):
        if self.top >= self.max_size - 1:
            raise Exception("Stack Overflow")
        self.top += 1
        self.array[self.top] = value
        return value

    def pop(self):
        if self.top < 0:
            raise Exception("Stack Underflow")
        value = self.array[self.top]
        self.array[self.top] = None
        self.top -= 1
        return value

    def peek(self):
        if self.top < 0:
            raise Exception("Stack is Empty")
        return self.array[self.top]

    def is_empty(self):
        return self.top < 0

    def is_full(self):
        return self.top >= self.max_size - 1

    def size(self):
        return self.top + 1