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PuzzlePlayer/Binary.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Drawing;
+using System.Linq;
 using System.Runtime.CompilerServices;
 
 namespace PuzzlePlayer_Namespace
@@ -83,7 +84,7 @@ namespace PuzzlePlayer_Namespace
         }
 
         private static int recursionDepth = 0;
-        private static int maxDepth = 500000;
+        private static int maxDepth = 1000000; // 1 mil recursions are allowed
 
         private static void PrintBoard(int[,] board)
         {
@@ -102,14 +103,14 @@ namespace PuzzlePlayer_Namespace
         // But i wrote all the code myself
         private static int[,] BackTrackAlgorithm(int[,] board)
         {
-            //recursionDepth++;
+            recursionDepth++;
             if (recursionDepth > maxDepth)
             {
-                Console.WriteLine("Max recursion depth reached.");
-                //return null;
+                Debug.WriteLine("Max recursion depth reached.");
+                return board;
             }
-
-            PrintBoard(board);
+            // print board for debugging
+            //PrintBoard(board);
 
             // check if the board is complete. if so then we can return the result
             if (IsBoardCompletlyFilledIn(board))
@@ -127,7 +128,7 @@ namespace PuzzlePlayer_Namespace
             }
 
             // check if the current board is already imposible to complete even tho there are still choices left
-            if (BoardIsImposible(board, choices))
+            if (!BoardIsPosible(board, choices))
                 return null;
 
             ///*
@@ -149,47 +150,53 @@ namespace PuzzlePlayer_Namespace
             // do the algorithm for every move
             foreach (Move m in choices)
             {
-                int[,] newBoard = (int[,])board.Clone();
+                int[,] newBoard = (int[,])board.Clone(); //create a shallow clone to avoid multiple paths refrencing the same object
 
                 newBoard[m.x,m.y] = m.changeTo;
-                
+
                 int[,] result = BackTrackAlgorithm(newBoard); // recursion for every move
 
                 if(result != null)
                     return result;
             }
 
-            //Debug.WriteLine("backtrack want moves empty");
             recursionDepth--;
+
             // if all choices fail then we should also return null
             return null;
         }
 
-        private static bool BoardIsImposible(int[,] board, List<Move> choices)
+        // checks if the board has a possible outcome to optimise the generating process
+        private static bool BoardIsPosible(int[,] board, List<Move> choices)
         {
-            throw new NotImplementedException();
-
-            bool isImposible = false;
+            if (choices.Count == 0) //if there are no choices then the board is imposible
+                return false;
 
-            List<int[]> locations = new List<int[]>();
+            List<(int, int)> emptyLocations = new List<(int, int)>();
 
             for (int i = 0; i < board.GetLength(0); i++)
+            {
                 for (int j = 0; j < board.GetLength(1); j++)
                 {
-                    if(board[i,j] == emptySpace)
-                        locations.Add([i,j]);
+                    if (board[i, j] == emptySpace)
+                        emptyLocations.Add((i, j));  //add all the empty locations to the list
                 }
+            }
 
-            foreach (Move m in choices)
+            // Verify each empty location has a valid move
+            foreach (Move move in choices)
             {
-                foreach (int[] i in locations)
+                if (emptyLocations.Contains((move.x, move.y)))
                 {
-                    if (m.x == i[0] && m.y == i[1])
-                        continue;
+                    emptyLocations.Remove((move.x, move.y));
+
+                    if (emptyLocations.Count == 0) // if there are none left we can return true
+                        return true;
                 }
             }
 
-            return isImposible;
+
+            return emptyLocations.Count == 0; // if there are none left we can return true
         }
 
         // get all the possible choices
@@ -204,50 +211,13 @@ namespace PuzzlePlayer_Namespace
                 for (int i = 0; i < board.GetLength(0); i++)
                     for (int j = 0; j < board.GetLength(1); j++)
                     {
-                        // if the checked space is already filled in than it is not a valid move
-                        //if (board[i, j] != emptySpace)
-                        //    continue;
-
-                        /*
-                        // if one of the checks succeeds then it is an invalid move
-                        if(DoAllChecks(i,j,board,checkFor))
-                            continue;
-                        //*/
-                        // if all checks pass then add the move to the list
-                        if(board[i, j] == emptySpace && ValidChoiceCheck(i,j,board,checkFor))
+                        if(board[i, j] == emptySpace && !DoAllChecks(i,j,board,checkFor))
                             choices.Add(new Move(i, j, checkFor));
                     }
             }
             return choices;
         }
 
-        private static bool ValidChoiceCheck(int x, int y, int[,] board, int checkFor)
-        {
-            int opposite;
-            if(checkFor == 0)
-                opposite = 1;
-            else
-                opposite = 0;
-
-            
-            if (SideCheck(x, y, board, checkFor))
-            {
-                //Debug.WriteLine("side check. return false");
-                return false;
-            }
-
-            if (MiddleCheck(x, y, board, checkFor))
-            {
-                //Debug.WriteLine("middle check. return false");
-                return false;
-            }
-
-            if(EvenCheck(x, y, board, checkFor))
-                return false;
-
-            return true;
-        }
-
         private static bool IsBoardCompletlyFilledIn(int[,] board)
         {
             for (int i = 0; i < board.GetLength(0); i++)