// #define Day3
#if Day3
using AoC2021;

var scans = File.ReadAllLines("day3/input").ToList();
var significantBitsList = scans.First().Select(c => c == '0' ? new SignificantBits() { zeros = 1 } : new SignificantBits() { ones = 1 }).ToList();
var indices = Enumerable.Range(0, significantBitsList.Count).ToList();
scans.Skip(1).ForEachAsList(bits => 
    bits.ForEachIndex((b, i) => {
        if (b == '0') {
            significantBitsList[i].zeros++;
        }
        else {
            significantBitsList[i].ones++;
        }
    }));

var gammaStr = String.Join("", significantBitsList.Select(s => s.ones > s.zeros ? "1" : "0"));
var epsilonStr= String.Join("", significantBitsList.Select(s => s.ones < s.zeros ? "1" : "0"));

var gamma = Convert.ToInt32(gammaStr, 2);
var epsilon = Convert.ToInt32(epsilonStr, 2);

Console.WriteLine(gamma * epsilon);

//Part2
int PartTwo(List<string>scans, Func<HashSet<int>, HashSet<int>, bool> check) {
    var toCheck = Enumerable.Range(0, scans.Count).ToHashSet();
    int index = 0;
    while (toCheck.Count() > 1) {
        var ones = new HashSet<int>();
        var zeros = new HashSet<int>();

        foreach (var o in toCheck) {
            if (scans[o][index] == '1') {
                ones.Add(o);
            }
            else {
                zeros.Add(o);
            }
        }

        if (check(ones, zeros)) {
            toCheck.ExceptWith(zeros);
        }
        else {
            toCheck.ExceptWith(ones);
        }

        index++;
    }

    return toCheck.First();
}

int oxygenLine = PartTwo(scans, (ones, zeros) => ones.Count >= zeros.Count);
int scrubberLine = PartTwo(scans, (ones, zeros) => ones.Count < zeros.Count);

int oxygen = Convert.ToInt32(scans[oxygenLine], 2);
int scrubber = Convert.ToInt32(scans[scrubberLine], 2);

Console.WriteLine(oxygen * scrubber); //400894

class SignificantBits {
    public int zeros { get; set; }
    public int ones { get; set; }
}
#endif