// Counts how many individual bags are required inside a shiny gold bag.
// Starts at shiny gold bag and go down the tree of contents.
public string PartTwo()
{
var BagsToContents = MapBagsToContents();
var nBags = 0;
var bagStack = new Stack <BagRequirement>();
foreach (var bag in BagsToContents["shiny gold"])
{
bagStack.Push(bag);
}
while (bagStack.Count > 0)
{
var currentBag = bagStack.Pop();
nBags += currentBag.nRequired;
if (BagsToContents.ContainsKey(currentBag.Bag))
{
foreach (var bag in BagsToContents[currentBag.Bag])
{
var newBag = new BagRequirement();
newBag.Bag = bag.Bag;
newBag.nRequired = bag.nRequired * currentBag.nRequired;
bagStack.Push(newBag);
}
}
}
return(nBags.ToString());
}
private void AddToBagsToContentsMap(string bag, string content, int nRequired, Dictionary <string, List <BagRequirement> > bagsToContents)
{
var newBag = new BagRequirement();
newBag.Bag = content;
newBag.nRequired = nRequired;
if (bagsToContents.ContainsKey(bag))
{
bagsToContents[bag].Add(newBag);
}
else
{
var bags = new List <BagRequirement>();
bags.Add(newBag);
bagsToContents.Add(bag, bags);
}
}