#define Day21
using System.Diagnostics;
using System.Threading.Channels;
using AoC2021;

#if Day21

var states = File.ReadAllLines("day21/input")
    .Select(l => new State() {pos = int.Parse(l[l.Length-1].ToString()) - 1, score = 0})
    .ToList();

// states = new List<State>() {
//     new State() {pos = 3, score = 0},
//     new State() {pos = 7, score = 0},
// };

var states2 = states.Select(s => s.Copy()).ToList();

var bla = Enumerable.Range(1, 3).SelectMany(x =>
        Enumerable.Range(1, 3).SelectMany(y => Enumerable.Range(1, 3).Select(z => new {x = x, y = y, z = z})))
    .Select(p => p.x + p.y + p.z).GroupBy(x => x).ToDictionary(x => x.Key, x => x.Count()); //ForEachAsList(p => Console.WriteLine(p));
bla.ForEachAsList(b => Console.WriteLine($"{b.Key}: {b.Value}"));
// System.Environment.Exit(0);

int curPlayer = 0;
int dieThrows = 0;
int deterministic = 99;

while (states[GetOtherPlayer(curPlayer)].score < 1000) {
    dieThrows += 3;
    var sumDie = GetDeterministic100Die().Take(3).Sum();
    states[curPlayer].pos += sumDie;
    states[curPlayer].pos %= 10;
    states[curPlayer].score += states[curPlayer].pos + 1;
    curPlayer = GetOtherPlayer(curPlayer);
}

var minScore = states.Select(s => s.score).Min();
Console.WriteLine(minScore * dieThrows);


//------------------

Stopwatch sw = new Stopwatch();
sw.Start();
Stack<CompleteState> stack = new Stack<CompleteState>();
stack.Push(new CompleteState(0, new StateRec(states2[0].pos, states2[0].score), new StateRec(states2[1].pos, states2[1].score), 1));

long countWin0 = 0;
long countWin1 = 0;

while (stack.Count > 0) {
    (int cur, StateRec p0, StateRec p1, long winTimes) = stack.Pop();
    StateRec curP = cur == 0 ? p0 : p1;
    AddState(Add(curP, 3), cur, p0, p1, winTimes * 1);
    AddState(Add(curP, 4), cur, p0, p1, winTimes * 3);
    AddState(Add(curP, 5), cur, p0, p1, winTimes * 6);
    AddState(Add(curP, 6), cur, p0, p1, winTimes * 7);
    AddState(Add(curP, 7), cur, p0, p1, winTimes * 6);
    AddState(Add(curP, 8), cur, p0, p1, winTimes * 3);
    AddState(Add(curP, 9), cur, p0, p1, winTimes * 1);
}
sw.Stop();
Console.WriteLine(sw.Elapsed);
Console.WriteLine(countWin0);
Console.WriteLine(countWin1);


StateRec Add(StateRec s, int die) {
    int newPos = (s.pos + die) % 10;
    return new StateRec(newPos, s.score + newPos + 1);
}


IEnumerable<int> GetDeterministic100Die() {
    while (true) {
        deterministic = (deterministic + 1) % 100;
        yield return deterministic + 1;    
    }
}

int GetOtherPlayer(int player) => player == 0 ? 1 : 0;

void AddState(StateRec stateRec, int curPlayer, StateRec p0, StateRec p1, long winTimes) {
    if (stateRec.score >= 21) {
        if (curPlayer == 0) {
            countWin0 += winTimes;
        } else {
            countWin1 += winTimes;
        }
    } else {
        if (curPlayer == 0) {
            stack.Push(new CompleteState(GetOtherPlayer(curPlayer), stateRec, p1, winTimes));
        } else {
            stack.Push(new CompleteState(GetOtherPlayer(curPlayer), p0, stateRec, winTimes));
        }
    }
}

class State {
    public int pos { get; set; }
    public int score { get; set; }

    public State Copy() {
        return new State() {pos = pos, score = score};
    }

    public override string ToString() {
        return $"Pos: {pos}, Score: {score}";
    }
}

record StateRec(int pos, int score);

record CompleteState(int curPlayer, StateRec player0, StateRec player1, long winTimes);
#endif