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

Last update on December 20 2024 12:53:03 (UTC/GMT +8 hours)

Write a C# program to sort the elements of a given stack in ascending 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 ascending order
    public static void SortAscending(Stack stack)
    {
        // Create a temporary stack to hold sorted elements
        Stack temp = new Stack(stack.items.Length);

        while (!stack.IsEmpty())
        {
            // Pop an element from the original stack
            int curr = stack.Pop();

            // Pop elements from the temporary stack and push them back onto the original stack
            while (!temp.IsEmpty() && temp.Peek() > curr)
            {
                stack.Push(temp.Pop());
            }

            // Push the current element onto the temporary stack
            temp.Push(curr);
        }

        // Copy the sorted elements back onto the original stack
        while (!temp.IsEmpty())
        {
            stack.Push(temp.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(1);
        stack.Push(3);
        stack.Push(3);
        stack.Push(9);
        stack.Push(5);
        Stack.Display(stack); // Displaying the elements in the stack

        Stack.SortAscending(stack); // Sorting stack elements in ascending order
        Console.WriteLine("\nStack elements in ascending 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 ascending order:");
        Stack.SortAscending(stack); // Sorting stack elements again in ascending 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 ascending order:
Stack elements:
1 3 3 5 9 
Input two more elements onto the stack:
Stack elements:
10 0 1 3 3 5 9 
Stack elements in ascending order:
Stack elements:
0 1 3 3 5 9 10

Flowchart:

C# Sharp Code Editor:

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