public static int GetMaxCost(Knapsack knapsack)
{
var items = knapsack.Items.Where(item => item.Weight <= knapsack.Capacity).ToArray();
var optimalSolution = new int[items.Length, knapsack.Capacity + 1];
for (int w = items[0].Weight; w <= knapsack.Capacity; w++)
{
optimalSolution[0, w] = items[0].Cost;
}
for (int i = 1; i < items.Length; i++)
{
var item = items[i];
for (int w = 1; w <= knapsack.Capacity; w++)
if (w < item.Weight)
{
optimalSolution[i, w] = optimalSolution[i - 1, w];
}
else
{
optimalSolution[i, w] = Math.Max(optimalSolution[i - 1, w], optimalSolution[i - 1, w - item.Weight] + item.Cost);
}
}
return optimalSolution[items.Length - 1, knapsack.Capacity];
}
public void GetBigKnapsackMaxCostTest()
{
var items = new[] { new KnapsackItem(3, 4), new KnapsackItem(2, 3), new KnapsackItem(4, 2), new KnapsackItem(4, 3) };
var knapsack = new Knapsack(items, 6);
var solver = new BigKnapsackSolver(knapsack);
solver.GetMaxCost().Should().Be(8);
}
public BigKnapsackSolver(Knapsack knapsack)
{
_items = new ReadOnlyCollection<KnapsackItem>(knapsack.Items.Where(item => item.Weight <= knapsack.Capacity).ToArray());
_capacity = knapsack.Capacity;
_calculatedMaxCosts = new Dictionary<int, int>[_items.Count];
for (int i = 0; i < _items.Count; i++)
{
_calculatedMaxCosts[i] = new Dictionary<int, int>();
}
}