Example #1
0
        //Dynamic programming algorithm
        private static Knapsack FillKnapsack(int maxWeight, List <Item> items)
        {
            Knapsack[] sacks = new Knapsack[maxWeight + 1];
            sacks[0] = new Knapsack(0);
            Knapsack bestSack;

            for (int w = 1; w <= maxWeight; w++)
            {
                bestSack = sacks[w - 1];
                sacks[w] = new Knapsack(w);
                for (int i = 0; i < items.Count; i++)
                {
                    int currVal    = items[i].value;
                    int currWeight = items[i].weight;
                    if (currWeight < w)
                    {
                        if ((sacks[w - currWeight].value + currVal) > bestSack.value)
                        {
                            bestSack = new Knapsack(w);
                            foreach (Item item in sacks[w - currWeight])
                            {
                                bestSack.Add(item);
                            }
                            bestSack.Add(items[i]);
                        }
                    }
                    else if (currWeight == w)
                    {
                        if (currVal > bestSack.value)
                        {
                            bestSack = new Knapsack(w);
                            bestSack.Add(items[i]);
                        }
                    }
                }
                sacks[w] = bestSack;
            }
            return(sacks[maxWeight]);
        }
Example #2
0
        public static void KnapsackProblem()
        {
            Console.WriteLine("Task#6 (items are infinite)");
            List <Item> items = new List <Item>();

            if (GetInput(items))
            {
                //Getting max weight capacity
                Console.WriteLine("Input an integer knapsack max weight capacity:");
                var consoleInput = Console.ReadLine();
                //Trying to parse the input
                int capacity = 0;
                if (!int.TryParse(consoleInput, out capacity) || capacity <= 0)
                {
                    Console.WriteLine($"\"{consoleInput}\" is too big, too small or is not an integer");
                    return;
                }

                Knapsack sack = FillKnapsack(capacity, items);

                //Writing contained items, sum of values and weights to console
                Console.WriteLine("Knapsack contains:");
                int sackWeight = 0;
                foreach (Item item in sack)
                {
                    Console.Write($"(v:{item.value}, w:{item.weight}) ");
                    sackWeight += item.weight;
                }
                Console.WriteLine($"\nSum: (v:{sack.value}, w:{sackWeight}/{capacity})\n" +
                                  $"Knapsack value is: {sack.value}");

                Console.WriteLine();
            }
            else
            {
                return;
            }
        }