private static int?GetMinimumMovesToTargetState(LockState target, LockState current, IEnumerable <LockState> deadEnds, int currentMin, int currentMoves, LockState previousState)
{
if (deadEnds.Any(s => s == current))
{
return(null);
}
if (current == target)
{
return(Math.Min(currentMin, currentMoves));
}
var nextMoves = new List <LockState>
{
current.MoveFirstClockwise(),
current.MoveSecondClockwise(),
current.MoveThirdClockwise(),
current.MoveFirstCounterClockwise(),
current.MoveSecondCounterClockwise(),
current.MoveThirdCounterClockwise(),
};
foreach (var nextMove in nextMoves)
{
if (nextMove == previousState)
{
continue;
}
currentMin = Math.Min(currentMin,
GetMinimumMovesToTargetState(target, nextMove, deadEnds, currentMin, currentMoves + 1, current) ?? int.MaxValue);
}
return(currentMin);
}