private static void PopulateBags()
{
int id = 0;
using (StreamReader reader = new StreamReader("./Challenge/input.txt", Encoding.UTF8))
{
while (reader.Peek() >= 0)
{
string[] parsedBag = LuggageParser.ParseBagEntry(reader.ReadLine());
string code = parsedBag[0].Trim();
BagColor bagColor = new BagColor()
{
Id = id,
Code = code,
CanContainsBags = new List <BagConnection>()
};
for (int i = 1; i < parsedBag.Length; i++)
{
if (parsedBag[i].Contains("no"))
{
bagColor.CanContainsBags.Add(new BagConnection()
{
Code = parsedBag[i].Trim(),
Quantity = 0
});
}
else
{
string[] parsedWithQuantity = parsedBag[i].Split(" ");
bagColor.CanContainsBags.Add(new BagConnection()
{
Code = parsedBag[i].Remove(0, parsedWithQuantity[0].Length).Trim(),
Quantity = int.Parse(parsedWithQuantity[0])
});
}
}
_bagColors.Add(bagColor);
id++;
}
}
}
/*
* 7. shiny gold bags contain 2 dark red bags.
* 6. dark red bags contain 2 dark orange bags.
* 5. dark orange bags contain 2 dark yellow bags.
* 4. dark yellow bags contain 2 dark green bags.
* 3. dark green bags contain 2 dark blue bags.
* 2. dark blue bags contain 2 dark violet bags.
* 1. dark violet bags contain no other bags.
*
* 2. quantity + 1 = 3
* 3. (2.) * quantity + 1 = 7
* 4. (3.) * quantity + 1 = 15
* 5. (4.) * quantity + 1 = 31
* 6. (5.) * quantity + 1 = 63
* 7. (6.) * quantity = 126
*/
public static int HowManyBagsCouldBagWithGivenCodeContains(string code)
{
int quantity = 0;
BagColor bagColor = _bagColors.SingleOrDefault(b => b.Code == code);
if (bagColor == null)
{
return(0);
}
foreach (BagConnection connection in bagColor.CanContainsBags)
{
//I didn't understand a sequense so the following formula was based on u/Zuuou solution. Thank you very much Zuuou!
//https://www.reddit.com/r/adventofcode/comments/k8a31f/2020_day_07_solutions/gexs8nu?utm_source=share&utm_medium=web2x&context=3
quantity += connection.Quantity * (HowManyBagsCouldBagWithGivenCodeContains(connection.Code) + 1);
}
return(quantity);
}