public (Dictionary <string, Allergen> Allergens, Dictionary <string, int> IngredientsCount) ParseInput(string input)
{
Dictionary <string, Allergen> allergens = new Dictionary <string, Allergen>();
Dictionary <string, int> ingredientsCount = new Dictionary <string, int>();
foreach (var line in input.Split(Environment.NewLine, StringSplitOptions.RemoveEmptyEntries))
{
var ingredientsAndAllergens = line.Split("(contains ");
var ingredients = ingredientsAndAllergens[0].Split(" ", StringSplitOptions.RemoveEmptyEntries);
var aller = ingredientsAndAllergens[1].Replace(")", "").Split(", ");
foreach (var a in aller)
{
if (allergens.ContainsKey(a))
{
allergens[a].AddIngredients(ingredients);
}
else
{
allergens[a] = new Allergen(a, ingredients);
}
}
foreach (var i in ingredients)
{
if (ingredientsCount.ContainsKey(i))
{
ingredientsCount[i]++;
}
else
{
ingredientsCount[i] = 1;
}
}
}
return(allergens, ingredientsCount);
}
public Ingredient(string nm)
{
Name = nm;
causes = null;
}
public void Part2()
{
List <Item> items = File.ReadAllLines("Day21Input.txt").Select(line => new Item(line)).ToList();
Dictionary <string, List <Item> > itemsByAllergen = new Dictionary <string, List <Item> >();
HashSet <string> allIngredients = new HashSet <string>();
foreach (Item item in items)
{
foreach (string ingredient in item.Ingredients)
{
allIngredients.Add(ingredient);
}
foreach (string allergen in item.Allergens)
{
if (!itemsByAllergen.TryGetValue(allergen, out List <Item> list))
{
list = new List <Item>();
itemsByAllergen.Add(allergen, list);
}
list.Add(item);
}
}
Dictionary <string, HashSet <string> > possibleIngredientsByAllergen = new Dictionary <string, HashSet <string> >();
foreach (string allergen in itemsByAllergen.Keys)
{
string[] intersection = itemsByAllergen[allergen].Select(i => i.Ingredients).Aggregate((x, y) => x.Intersect(y).ToArray()).ToArray();
possibleIngredientsByAllergen.Add(allergen, new HashSet <string>(intersection));
}
foreach (string ingredient in possibleIngredientsByAllergen.Values.SelectMany(arr => arr.Select(i => i)))
{
allIngredients.Remove(ingredient);
}
foreach (string ingredient in allIngredients /* now non-allergen ingredients */)
{
foreach (HashSet <string> set in possibleIngredientsByAllergen.Values)
{
set.Remove(ingredient);
}
}
List <Allergen> unsolvedAllergens = possibleIngredientsByAllergen.Select(kvp => new Allergen()
{
Name = kvp.Key, PossibleIngredients = kvp.Value
}).ToList();
List <Allergen> solvedAllergens = new List <Allergen>();
while (unsolvedAllergens.Count > 0)
{
Allergen current = unsolvedAllergens.First(a => a.PossibleIngredients.Count == 1);
unsolvedAllergens.Remove(current);
solvedAllergens.Add(current);
current.Ingredient = current.PossibleIngredients.Single();
foreach (Allergen a in unsolvedAllergens)
{
a.PossibleIngredients.Remove(current.Ingredient);
}
}
string[] resultArray = solvedAllergens.OrderBy(a => a.Name).Select(a => a.Ingredient).ToArray();
string result = string.Join(",", resultArray);
Assert.Equal("ktpbgdn,pnpfjb,ndfb,rdhljms,xzfj,bfgcms,fkcmf,hdqkqhh", result);
}