Data commit

Task/Sokoban/C-sharp/sokoban.cs

@@ -0,0 +1,174 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace SokobanSolver
+{
+    public class SokobanSolver
+    {
+        private class Board
+        {
+            public string Cur { get; internal set; }
+            public string Sol { get; internal set; }
+            public int X { get; internal set; }
+            public int Y { get; internal set; }
+
+            public Board(string cur, string sol, int x, int y)
+            {
+                Cur = cur;
+                Sol = sol;
+                X = x;
+                Y = y;
+            }
+        }
+
+        private string destBoard, currBoard;
+        private int playerX, playerY, nCols;
+
+        SokobanSolver(string[] board)
+        {
+            nCols = board[0].Length;
+            StringBuilder destBuf = new StringBuilder();
+            StringBuilder currBuf = new StringBuilder();
+
+            for (int r = 0; r < board.Length; r++)
+            {
+                for (int c = 0; c < nCols; c++)
+                {
+
+                    char ch = board[r][c];
+
+                    destBuf.Append(ch != '$' && ch != '@' ? ch : ' ');
+                    currBuf.Append(ch != '.' ? ch : ' ');
+
+                    if (ch == '@')
+                    {
+                        this.playerX = c;
+                        this.playerY = r;
+                    }
+                }
+            }
+            destBoard = destBuf.ToString();
+            currBoard = currBuf.ToString();
+        }
+
+        private string Move(int x, int y, int dx, int dy, string trialBoard)
+        {
+
+            int newPlayerPos = (y + dy) * nCols + x + dx;
+
+            if (trialBoard[newPlayerPos] != ' ')
+                return null;
+
+            char[] trial = trialBoard.ToCharArray();
+            trial[y * nCols + x] = ' ';
+            trial[newPlayerPos] = '@';
+
+            return new string(trial);
+        }
+
+        private string Push(int x, int y, int dx, int dy, string trialBoard)
+        {
+
+            int newBoxPos = (y + 2 * dy) * nCols + x + 2 * dx;
+
+            if (trialBoard[newBoxPos] != ' ')
+                return null;
+
+            char[] trial = trialBoard.ToCharArray();
+            trial[y * nCols + x] = ' ';
+            trial[(y + dy) * nCols + x + dx] = '@';
+            trial[newBoxPos] = '$';
+
+            return new string(trial);
+        }
+
+        private bool IsSolved(string trialBoard)
+        {
+            for (int i = 0; i < trialBoard.Length; i++)
+                if ((destBoard[i] == '.')
+                        != (trialBoard[i] == '$'))
+                    return false;
+            return true;
+        }
+
+        private string Solve()
+        {
+            char[,] dirLabels = { { 'u', 'U' }, { 'r', 'R' }, { 'd', 'D' }, { 'l', 'L' } };
+            int[,] dirs = { { 0, -1 }, { 1, 0 }, { 0, 1 }, { -1, 0 } };
+            ISet<string> history = new HashSet<string>();
+            LinkedList<Board> open = new LinkedList<Board>();
+
+            history.Add(currBoard);
+            open.AddLast(new Board(currBoard, string.Empty, playerX, playerY));
+
+            while (!open.Count.Equals(0))
+            {
+                Board item = open.First();
+                open.RemoveFirst();
+                string cur = item.Cur;
+                string sol = item.Sol;
+                int x = item.X;
+                int y = item.Y;
+
+                for (int i = 0; i < dirs.GetLength(0); i++)
+                {
+                    string trial = cur;
+                    int dx = dirs[i, 0];
+                    int dy = dirs[i, 1];
+
+                    // are we standing next to a box ?
+                    if (trial[(y + dy) * nCols + x + dx] == '$')
+                    {
+                        // can we push it ?
+                        if ((trial = Push(x, y, dx, dy, trial)) != null)
+                        {
+                            // or did we already try this one ?
+                            if (!history.Contains(trial))
+                            {
+
+                                string newSol = sol + dirLabels[i, 1];
+
+                                if (IsSolved(trial))
+                                    return newSol;
+
+                                open.AddLast(new Board(trial, newSol, x + dx, y + dy));
+                                history.Add(trial);
+                            }
+                        }
+                        // otherwise try changing position
+                    }
+                    else if ((trial = Move(x, y, dx, dy, trial)) != null)
+                    {
+                        if (!history.Contains(trial))
+                        {
+                            string newSol = sol + dirLabels[i, 0];
+                            open.AddLast(new Board(trial, newSol, x + dx, y + dy));
+                            history.Add(trial);
+                        }
+                    }
+                }
+            }
+            return "No solution";
+        }
+
+        public static void Main(string[] a)
+        {
+            string level = "#######," +
+                           "#     #," +
+                           "#     #," +
+                           "#. #  #," +
+                           "#. $$ #," +
+                           "#.$$  #," +
+                           "#.#  @#," +
+                           "#######";
+            System.Console.WriteLine("Level:\n");
+            foreach (string line in level.Split(','))
+            {
+                System.Console.WriteLine(line);
+            }
+            System.Console.WriteLine("\nSolution:\n");
+            System.Console.WriteLine(new SokobanSolver(level.Split(',')).Solve());
+        }
+    }
+}