protected override void TryAddCell(int currentIndexValue, int currentItemIndex, int maxWeight, Queue <int> toVisitNext, KnapsackItem item = null)
{
var currentCell = memoryTable[currentIndexValue, currentItemIndex];
var newWeight = currentCell.Value;
var newPrice = currentIndexValue;
if (item != null)
{
newPrice += item.Price;
newWeight += item.Weight;
}
//Weight limit reached
if (newWeight > maxWeight)
{
return;
}
var nextCell = memoryTable[newPrice, currentItemIndex + 1];
//Add the new cell into the table if it is better than the one previously placed there
if (nextCell == null || nextCell.Value > newWeight)
{
memoryTable[newPrice, currentItemIndex + 1] = new DPCell
{
AddedItem = (item != null),
PreviousCell = currentCell,
Value = newWeight
};
toVisitNext.Enqueue(newPrice);
}
}
protected List <bool> GetItemVector(DPCell lastCell)
{
var itemsVector = new List <bool>();
var currentCell = lastCell;
while (currentCell != null)
{
itemsVector.Add(currentCell.AddedItem);
currentCell = currentCell.PreviousCell;
}
itemsVector.Reverse();
return(itemsVector);
}
private DPCell FindBestCell(KnapsackInstance instance)
{
DPCell bestCell = memoryTable[toVisit.Dequeue(), instance.ItemCount - 1];
foreach (var weightIndex in toVisit)
{
var currentCell = memoryTable[weightIndex, instance.ItemCount - 1];
if (currentCell.Value > bestCell.Value)
{
bestCell = currentCell;
}
}
return(bestCell);
}
protected override void InitializeTable(KnapsackInstance instance)
{
memoryTable = new DPCell[instance.KnapsackSize + 1, instance.ItemCount];
toVisit = new Queue <int>();
toVisit.Enqueue(0);
memoryTable[0, 0] = new DPCell {
AddedItem = false, Value = 0
};
var firstItem = instance.Items.First();
if (firstItem.Weight <= instance.KnapsackSize)
{
toVisit.Enqueue(firstItem.Weight);
memoryTable[firstItem.Weight, 0] = new DPCell {
AddedItem = true, Value = firstItem.Price
};
}
}
