#define Day6
#if Day6
var fish = File.ReadAllText("day6/input").Split(",")
    .Select(long.Parse)
    .GroupBy(x => x)
    .ToDictionary(x => x.Key, x => x.LongCount());

fish[0] = 0;
fish[6] = 0;
fish[7] = 0;
fish[8] = 0;

Console.WriteLine(CalculateGrowth(80, Copy(fish)));
Console.WriteLine(CalculateGrowth(256, Copy(fish)));

long CalculateGrowth(int numberOfDays, Dictionary<long, long> fishState) {
    while (numberOfDays > 0) {
        long newFish = fishState[0];
        for (int i = 0; i < 8; i++) {
            fishState[i] = fishState[i + 1];
        }
        fishState[6] += newFish;
        fishState[8] = newFish;

        numberOfDays--;
    }
    return fishState.Values.Sum();
}

Dictionary<long, long> Copy(Dictionary<long, long> dict) {
    return dict.ToDictionary(entry => entry.Key,
        entry => entry.Value);
}
#endif