C#: Sort the elements of a stack in descending order

C# Sharp Stack: Exercise-2 with Solution

Write a C# program to sort the elements of a given stack in descending order.

Sample Solution:

C# Code:

using System;
// 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 sort the stack elements in descending order
    public static void SortDescending(Stack stack)
    {
        if (stack.IsEmpty())
        {
            Console.WriteLine("Stack is empty");
            return;
        }
        // Creating a temporary stack to hold sorted elements
        Stack tempStack = new Stack(stack.items.Length);
        // Sorting elements in descending order
        while (!stack.IsEmpty())
        {
            int currentItem = stack.Pop();
            while (!tempStack.IsEmpty() && currentItem > tempStack.Peek())
            {
                stack.Push(tempStack.Pop());
            }
            tempStack.Push(currentItem);
        }
        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("\nInput some elements onto the stack:");
        stack.Push(1);
        stack.Push(3);
        stack.Push(3);
        stack.Push(9);
        stack.Push(5);
        Stack.Display(stack); // Displaying the elements in the stack
        Stack.SortDescending(stack); // Sorting stack elements in descending order
        Console.WriteLine("\nStack elements in descending order:");
        Stack.Display(stack); // Displaying the sorted elements
        Console.WriteLine("\nInput two more elements onto the stack:");
        stack.Push(0);
        stack.Push(10);
        Stack.Display(stack);
        Console.WriteLine("\nStack elements in descending order:");
        Stack.SortDescending(stack); // Sorting stack elements again in descending order
        Stack.Display(stack); // Displaying the sorted elements
    }
}

Sample Output:

Initialize a stack:

Input some elements onto the stack:
Stack elements:
5 9 3 3 1 
Stack elements in descending order:
Stack elements:
9 5 3 3 1 
Input two more elements onto the stack:
Stack elements:
10 0 9 5 3 3 1 
Stack elements in descending order:
Stack elements:
10 9 5 3 3 1 0 

Flowchart:

C# Sharp Code Editor:

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