public static int Part2(Problem problem)
{
var player1Cards = new Queue <int>(problem.Player1Cards);
var player2Cards = new Queue <int>(problem.Player2Cards);
var recursionWatchdog = new RecursionWatchdog();
var player1WonBecauseOfRecursion = PlaySubGame(player1Cards, player2Cards);
var winnerDeck = player1Cards.Count > 0 || player1WonBecauseOfRecursion ? player1Cards : player2Cards;
return(GetScore(winnerDeck));
}
private static bool PlaySubGame(Queue <int> player1Cards, Queue <int> player2Cards)
{
var recursionWatchdog = new RecursionWatchdog();
while (player1Cards.Count > 0 && player2Cards.Count > 0)
{
if (recursionWatchdog.IsAlreadyPlayedRound(player1Cards, player2Cards))
{
return(true);
}
recursionWatchdog.AddRound(player1Cards, player2Cards);
var player1Card = player1Cards.Dequeue();
var player2Card = player2Cards.Dequeue();
if (player1Card <= player1Cards.Count && player2Card <= player2Cards.Count)
{
var subGamePlayer1Cards = new Queue <int>(player1Cards.ToList().Take(player1Card));
var subGamePlayer2Cards = new Queue <int>(player2Cards.ToList().Take(player2Card));
var player1WonBecauseOfRecursion = PlaySubGame(subGamePlayer1Cards, subGamePlayer2Cards);
if (subGamePlayer1Cards.Count > 0 || player1WonBecauseOfRecursion)
{
player1Cards.Enqueue(player1Card);
player1Cards.Enqueue(player2Card);
}
else
{
player2Cards.Enqueue(player2Card);
player2Cards.Enqueue(player1Card);
}
}
else
{
if (player1Card > player2Card)
{
player1Cards.Enqueue(player1Card);
player1Cards.Enqueue(player2Card);
}
else
{
player2Cards.Enqueue(player2Card);
player2Cards.Enqueue(player1Card);
}
}
}
return(false);
}