C#: Remove duplicates from a given stack

C# Sharp Stack: Exercise-12 with Solution

Write a C# program to remove duplicates from a given stack.

Sample Solution:

C# Code:

using System;
using System.Collections.Generic;

// Implementation of a Stack data structure
public class Stack
{
    private int[] items; // Array to hold stack elements
    private int top;     // Index representing the top of the stack

    // Constructor to initialize the stack with a specified size
    public Stack(int size)
    {
        items = new int[size]; // Initializing the array with the given size
        top = -1;              // Initializing top to -1, indicating an empty stack
    }

    // Method to check if the stack is empty
    public bool IsEmpty()
    {
        return top == -1; // Returns true if top is -1 (empty stack), otherwise false
    }

    // Method to check if the stack is full
    public bool IsFull()
    {
        return top == items.Length - 1; // Returns true if top is at the last index of the array (full stack)
    }

    // Method to push an element onto the stack
    public void Push(int item)
    {
        if (IsFull())
        {
            Console.WriteLine("Stack Full!"); // Displays a message if the stack is full
            return;
        }

        items[++top] = item; // Inserts the item at the incremented top index
    }

    // Method to pop an element from the stack
    public int Pop()
    {
        if (IsEmpty())
        {
            Console.WriteLine("Stack underflow"); // Displays a message if the stack is empty
            return -1;
        }

        return items[top--]; // Removes and returns the top element by decrementing top
    }

    // Method to peek at the top element of the stack without removing it
    public int Peek()
    {
        if (IsEmpty())
        {
            Console.WriteLine("Stack is empty"); // Displays a message if the stack is empty
            return -1;
        }

        return items[top]; // Returns the element at the top index without removing it
    }

    // Method to get the current size of the stack
    public static int Size(Stack stack)
    {
        return stack.top + 1; // Returns the number of elements in the stack
    }

    // Method to remove duplicate elements from the stack
    public static void Remove_Duplicates(Stack stack)
    {
        if (stack == null || stack.IsEmpty())
            return;

        HashSet<int> set = new HashSet<int>(); // HashSet to store unique elements

        Stack tempStack = new Stack(Size(stack)); // Temporary stack to store unique elements

        while (!stack.IsEmpty())
        {
            int current = stack.Pop();

            // If the set doesn't contain the current element, it's unique, so add it to the set and tempStack
            if (!set.Contains(current))
            {
                set.Add(current);
                tempStack.Push(current);
            }
        }

        // Restoring original stack order by pushing elements from tempStack back to the original stack
        while (!tempStack.IsEmpty())
        {
            stack.Push(tempStack.Pop());
        }
    }

    // Method to display the stack elements
    public static void Display(Stack stack)
    {
        if (stack.IsEmpty())
        {
            Console.WriteLine("Stack is empty");
            return;
        }

        Console.WriteLine("Stack elements:");
        for (int i = stack.top; i >= 0; i--)
        {
            Console.Write(stack.items[i] + " "); // Displays each element in the stack
        }
    }
}

// Main class to demonstrate the functionality of the Stack class
public class Program
{
    public static void Main(string[] args)
    {
        Console.WriteLine("Initialize a stack:");
        Stack stack = new Stack(10); // Creating a stack with a size of 10

        Console.WriteLine("Input some elements onto the stack:");
        stack.Push(10);
        stack.Push(50);
        stack.Push(30);
        stack.Push(40);
        stack.Push(50);
        stack.Push(50);
        stack.Push(10);
        Stack.Display(stack); // Displaying the elements in the original stack

        Console.WriteLine("\nRemove duplicates from the said stack:");
        Stack.Remove_Duplicates(stack); // Removing duplicate elements from the stack
        Stack.Display(stack); // Displaying the elements in the stack after removing duplicates
    }
}

Sample Output:

Initialize a stack:
Input some elements onto the stack:
Stack elements:
10 50 50 40 30 50 10 
Remove duplicates from the said stack:
Stack elements:
10 50 40 30 

Flowchart:

C# Sharp Code Editor:

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