public static BagRules Parse(string rule)
{
rule = rule
.Replace("bags", "")
.Replace("bag", "")
.Replace(".", "");
var bagAndContains = rule.Split("contain");
var name = bagAndContains[0].Trim();
var containedBags = bagAndContains[1].Split(',');
Dictionary <string, int> canContain;
if (containedBags[0].Trim() == "no other")
{
canContain = new Dictionary <string, int>();
}
else
{
canContain = containedBags
.Select(cb => cb.Split(" ", StringSplitOptions.RemoveEmptyEntries))
.ToDictionary(
b => $"{b[1]} {b[2]}",
b => int.Parse(b[0]));
}
var bag = new BagRules(name, canContain);
return(bag);
}
/// <summary>
/// How many outer bags can carry a shiny gold one?
/// </summary>
public static int Solve(string bagRules)
{
var rules = bagRules
.Split(Environment.NewLine)
.Select(br => BagRules.Parse(br));
var bags = new Bags(rules);
return(bags.CountShinyGold());
}
private static bool ContainsGold(BagRules rule, IEnumerable <BagRules> rules)
{
if (!rule.CouldHold.Any())
{
return(false);
}
else if (rule.CouldHold.Keys.Contains(Day7.ShinyGold))
{
return(true);
}
else
{
return(rules
.Where(r => rule.CouldHold.ContainsKey(r.Name))
.Any(r => ContainsGold(r, rules)));
}
}
