public override object SolveOne() { return(IntRows .Where(x => IntRows.Contains(2020 - x)) .Select(x => x * (2020 - x)) .First()); }
long CountPaths(int current) { if (current == Max) { return(1); } return(IntRows.Where(x => x > current && x <= current + 3).Sum(x => { if (!Memo.ContainsKey(x)) { Memo[x] = CountPaths(x); } return Memo[x]; })); }
public override object SolveOne() { int[] hops = new int[] { 0, 0, 0 }; int joltage = 0; while (true) { if (joltage == Max) { return(hops[0] * (hops[2] + 1)); } int next = IntRows.Where(x => x > joltage).Min(); hops[next - joltage - 1]++; joltage = next; } }
public override object SolveTwo() { return(IntRows .Where(x => IntRows.Exists(y => IntRows.Contains(2020 - x - y))) .Aggregate(1, (x, y) => x * y)); }
public Day10() { Max = IntRows.Max(); }