C# Program to Calculate Change Using the Largest Possible Coins and Bills

using System;

class Program
{
    static void Main()
    {
        // Ask for the price of the item
        Console.Write("Price? ");
        int price = int.Parse(Console.ReadLine()); // Read the price from the user
        
        // Ask for the amount paid by the customer
        Console.Write("Paid? ");
        int paid = int.Parse(Console.ReadLine()); // Read the amount paid from the user

        // Calculate the change to be given
        int change = paid - price; 
        
        // Check if the amount paid is less than the price
        if (change < 0)
        {
            Console.WriteLine("Not enough money paid!");
            return;
        }

        // Output the total change
        Console.WriteLine($"Your change is {change}:");

        // List of coin/bill denominations in descending order
        int[] denominations = { 100, 50, 20, 10, 5, 2, 1 };

        // Loop through each denomination and determine how many times it can be used
        foreach (int denomination in denominations)
        {
            while (change >= denomination)
            {
                Console.Write(denomination + " "); // Print the denomination
                change -= denomination; // Subtract the denomination value from the remaining change
            }
        }
        
        Console.WriteLine(); // Move to the next line after printing all denominations
    }
}

 Output

//Example 1:
Price? 44
Paid? 100
Your change is 56:
50 5 1 

//Example 2:
Price? 1
Paid? 100
Your change is 99:
50 20 20 5 2 2

//Example 3 (Edge Case):
Price? 60
Paid? 100
Your change is 40:
20 20

//Example 4 (Error Case):
Price? 200
Paid? 100
Not enough money paid!