private void GetMinPrice(TrolleyCalculatorInput input, decimal maxPrice, List <Special> specials, Dictionary <string, long> shoppedProducts, ref decimal minPrice, int i, ref bool minPriceUpdated, int j)
{
var specialCounts = new List <int>();
specialCounts.InitList(i, specials.Count);
var more = true;
for (var k = j; more; ++k)
{
int oldValue = specialCounts[j];
specialCounts[j] = oldValue + k;
if (this.IsApplicable(shoppedProducts, specials, specialCounts))
{
var priceForSpecials = this.GetPriceForSpecials(specials, specialCounts);
if (maxPrice > priceForSpecials)
{
var priceForRest = this.GetPriceForNonSpecials(input.Products, specials, specialCounts, shoppedProducts);
var price = priceForSpecials + priceForRest;
if (price < minPrice)
{
minPrice = price;
minPriceUpdated = true;
}
specialCounts[j] = oldValue;
}
}
else
{
more = false;
}
}
}
public void TestGetMinPriceWith0()
{
var service = new ProductService(new MockResourceService());
var input = new TrolleyCalculatorInput()
{
Products = new List <Product>()
{
new Product {
Name = MockResourceService.ProductNameA, Price = 0
}
},
Quantities = new List <Product>()
{
new Product {
Name = MockResourceService.ProductNameA, Quantity = 0
}
},
Specials = new List <Special>()
{
new Special
{
Total = 5,
Quantities = new List <Product>()
{
new Product {
Name = MockResourceService.ProductNameA, Quantity = 0
}
}
}
}
};
Assert.AreEqual(service.GetMinPrice(input).Total, 0);
Assert.AreEqual(service.GetMinPriceAsDecimal(input), 0);
}
/// <summary>
/// Returns the lowest possible total based on provided lists of prices, specials and quantities.
/// </summary>
/// <param name="input">An instance of TrolleyCalculatorInput with prices, specials and quantities</param>
/// <returns>An instance of TrolleyCalculatorOutput with the lowest possible total</returns>
public TrolleyCalculatorOutput GetMinPrice(TrolleyCalculatorInput input)
{
if (input == null)
{
return(this.CreateTrolleyCalculatorOutput(0));
}
var maxPrice = this.GetMaxPrice(input);
if (maxPrice == 0)
{
return(this.CreateTrolleyCalculatorOutput(0));
}
var specials = this.GetApplicableSpecials(input, maxPrice);
var shoppedProducts = this.GetShoppedProducts(input);
var minPrice = maxPrice;
var i = 0;
var minPriceUpdated = false;
while (!minPriceUpdated)
{
minPriceUpdated = false;
for (var j = 0; j < specials.Count; ++j)
{
this.GetMinPrice(input, maxPrice, specials, shoppedProducts, ref minPrice, i, ref minPriceUpdated, j);
}
i++;
}
return(this.CreateTrolleyCalculatorOutput(minPrice));
}
private List <Special> GetApplicableSpecials(TrolleyCalculatorInput input, decimal maxPrice)
{
// The price is less than the max price when buying the individual items.
var result = input.Specials.Where(s => s.Total < maxPrice).ToList();
// Should not to have any products that are not in the shopping cart.
var shoppedProductNames = input.Quantities.Select(q => q.Name).ToList();
result = result.Where(s => s.Quantities.All(q => shoppedProductNames.Contains(q.Name))).ToList();
// Should not to have more products than the requested quantity.
var shoppedProductQuntities = input.Quantities.ToDictionary(q => q.Name, q => q.Quantity);
return(result.Where(s => s.Quantities.All(q => { shoppedProductQuntities.TryGetValue(q.Name, out long v); return v >= q.Quantity; })).ToList());
}
private decimal GetMaxPrice(TrolleyCalculatorInput input)
{
decimal price = 0;
foreach (Product quantity in input.Quantities)
{
foreach (Product product in input.Products)
{
if (product.Name == quantity.Name)
{
price += quantity.Quantity * product.Price;
break;
}
}
}
return(price);
}
/// <summary> /// Returns the lowest possible total based on provided lists of prices, specials and quantities. /// </summary> /// <param name="input">An instance of TrolleyCalculatorInput with prices, specials and quantities</param> /// <returns>The lowest possible total as decimal</returns> public decimal GetMinPriceAsDecimal(TrolleyCalculatorInput input) => (decimal)this.GetMinPrice(input).Total;
private Dictionary <string, long> GetShoppedProducts(TrolleyCalculatorInput input)
{
return(input.Quantities.ToDictionary(q => q.Name, q => q.Quantity));
}