/// <summary>
/// Generates a random amount of each physical denomination that adds up to the amount of change owed.
/// </summary>
/// <param name="totalChange">The total amount of change owed to the customer.</param>
/// <returns>A string containing a random amount of physical change owed given the amount owed/paid.</returns>
public static string CalculateRandomChange(decimal totalChange)
{
var denominations = new[] { 100.00m, 50.00m, 20.00m, 10.00m, 5.00m, 1.00m, 0.25m, 0.10m, 0.05m, 0.01m };
var changeResult = new ChangeResult();
foreach (var denomination in denominations)
{
if (denomination > totalChange)
{
continue;
}
// if we're on the last iteration, set pennies equal to the total change remaining
if (denomination == 0.01m)
{
changeResult.AddDenomination(denomination, (int)(totalChange * 100));
break;
}
// we can use this denomination, so lets find a random value we can use
var randomAmount = Random.Next(0, (int)(totalChange / denomination));
totalChange -= denomination * randomAmount;
changeResult.AddDenomination(denomination, randomAmount);
}
return(changeResult.ToString());
}
/// <summary>
/// Uses integer math to provide the least physical amount of change to provide back to the customer.
/// </summary>
/// <param name="totalChange">The total amount of change owed to the customer.</param>
/// <returns>A string containing the lowest amount of physical change possible given the amount owed/paid.</returns>
public static string CalculateLowestAmountOfChange(decimal totalChange)
{
// convert to use integer math below.
var changeInt = (int)Math.Round(totalChange * 100);
var result = new ChangeResult();
result.Hundreds += changeInt / 10000;
changeInt %= 10000;
result.Fifties += changeInt / 5000;
changeInt %= 5000;
result.Twenties += changeInt / 2000;
changeInt %= 2000;
result.Tens += changeInt / 1000;
changeInt %= 1000;
result.Fives += changeInt / 500;
changeInt %= 500;
result.Dollars += changeInt / 100;
changeInt %= 100;
result.Quarters += changeInt / 25;
changeInt %= 25;
result.Dimes += changeInt / 10;
changeInt %= 10;
result.Nickles += changeInt / 5;
changeInt %= 5;
result.Pennies += changeInt;
return(result.ToString());
}