private static int SolveBoard(List <string> board)
{
var boardsToExplore = new Queue <BoardWithLevel>();
var startingBoard = new BoardWithLevel(board, FindEmptySquare(board));
boardsToExplore.Enqueue(startingBoard);
var seenBoards = new Dictionary <string, bool>();
while (boardsToExplore.Count > 0)
{
var currentBoard = boardsToExplore.Dequeue();
if (BoardIsComplete(currentBoard))
{
return(currentBoard.Level);
}
var currentBoardKey = string.Join("", currentBoard);
if (seenBoards.ContainsKey(currentBoardKey))
{
continue;
}
seenBoards.Add(currentBoardKey, true);
var numberOfMisplacedPieces = NumberOfMisplacedPieces(currentBoard);
var minimumTotalMoves = (numberOfMisplacedPieces - 1) + currentBoard.Level;
if (currentBoard.Level < 10 && minimumTotalMoves < 11)
{
var emptySquare = currentBoard.EmptySquarePosition;
var possibleMoves = GetAllPossibleMoves(emptySquare);
foreach (var move in possibleMoves)
{
var newBoard = CreateUpdatedBoard(currentBoard, emptySquare, move);
var newBoardKey = string.Join("", newBoard);
if (!seenBoards.ContainsKey(newBoardKey))
{
boardsToExplore.Enqueue(new BoardWithLevel(newBoard.ToList(), move, currentBoard.Level + 1));
}
}
}
}
return(11);
}
private static string[] CreateUpdatedBoard(BoardWithLevel currentBoard, Position emptySquare, Position move)
{
var newBoard = new string[5];
currentBoard.CopyTo(newBoard);
var theRow = newBoard[emptySquare.Row].ToCharArray();
theRow[emptySquare.Column] = newBoard[move.Row][move.Column];
newBoard[emptySquare.Row] = new string(theRow);
theRow = newBoard[move.Row].ToCharArray();
theRow[move.Column] = ' ';
newBoard[move.Row] = new string(theRow);
return(newBoard);
}
