public int PartTwo()
{
var game = new CrabRecursiveCombat(_player1, _player2);
var(player1, player2) = game.Play();
return(Math.Max(player1.Score(), player2.Score()));
}
public (IEnumerable <int> Player1, IEnumerable <int> Player2) Play()
{
while (_player1.Count > 0 && _player2.Count > 0)
{
// Before either player deals a card, if there was a previous round in this game that had exactly
// the same cards in the same order in the same players' decks,the game instantly ends in a win for
// player 1
if (!_rounds.Add(_player1.Concat(_player2)))
{
return(_player1.ToArray(), Enumerable.Empty <int>());
}
// Otherwise, this round's cards must be in a new configuration; the players begin the round by each
// drawing the top card of their deck as normal
var card1 = _player1.Dequeue();
var card2 = _player2.Dequeue();
var player1Wins = card1 > card2;
if (card1 <= _player1.Count && card2 <= _player2.Count)
{
// To play a sub-game of Recursive Combat, each player creates a new deck by making a copy of the
// next cards in their deck (the quantity of cards copied is equal to the number on the card they
// drew to trigger the sub-game).
var subGame = new CrabRecursiveCombat(_player1.Take(card1), _player2.Take(card2));
var(p1, p2) = subGame.Play();
player1Wins = p1.Any();
}
if (player1Wins)
{
_player1.Enqueue(card1);
_player1.Enqueue(card2);
}
else
{
_player2.Enqueue(card2);
_player2.Enqueue(card1);
}
}
return(_player1, _player2);
}