public class LineCore
   {
       //整体宽度
       public int width { get; set; }
       //整体高度
       public int height { get; set; }
       //前次被点击的图片
       public Position lastPicture { get; set; }
       //当前被电击的图片
       public Position currentPicture { get; set; }
       // 图片矩阵，-1表示没有图片，初始化时，任意matrix[x,y]当x==0或y==0时，matrix[x,y]=-1
       public int[,] matrix { get; set; }

       public bool testLine(Position current)
       {
           //上次连接成功后，第一次点击,
           if (currentPicture == null)
           {
               currentPicture = current;
               return false;
           }
           //连续点击了同一幅图片
           if (currentPicture.x==current.x&&currentPicture.y==current.y)
           {
               return false;
           }
           //不是相同的图像，不能消除
           if (current.picture != currentPicture.picture)
           {
               lastPicture = null;
               currentPicture = current;
               return false;
           }
           lastPicture = currentPicture;
           currentPicture = current;
           //记录连接路径
           List<Position> paths = new List<Position>();
           paths.Add(currentPicture);
           bool finded=false;
           //向东搜索
           finded = _find(paths, 2, Direct.East, lastPicture);
           if (finded)
           {
               return true;
           }
           //向南搜索
           finded = _find(paths, 2, Direct.South, lastPicture);
           if (finded)
           {
               return true;
           }
           //向西搜索
           finded = _find(paths, 2, Direct.West, lastPicture);
           if (finded)
           {
               return true;
           }
           //向北搜索
           finded = _find(paths, 2, Direct.North, lastPicture);
           if (finded)
           {
               return true;
           }
           //搜索失败
           return false;
       }
       /***
        * results-> 搜索路径
        * chance-> 还剩有转弯的机会，最多2次
        * direct-> 当前前进的方向 
        * target-> 搜索的目标
        * **/
       protected bool _find(List<Position> results, int chance, Direct direct, Position target)
       {
           //路径中不能为空
           if (results.Count <= 0)
           {
               return false;
           }
           //取路径中最后一个
           Position currentPos = results.ElementAt(results.Count - 1);
           //构造下一个将要检测的路径
           Position nextPos = new Position();
           switch(direct){
               case Direct.East:
                   nextPos.x=currentPos.x+1;
                   nextPos.y=currentPos.y;
                   break;
                   case Direct.West:
                   nextPos.x=currentPos.x-1;
                   nextPos.y=currentPos.y;
                   break;
                   case Direct.South:
                   nextPos.x=currentPos.x;
                   nextPos.y=currentPos.y+1;
                   break;
                   case Direct.North:
                   nextPos.x=currentPos.x;
                   nextPos.y=currentPos.y-1;
                   break;
           }
           bool overFlow = false;
           //检测是否已经走出边界
           if (nextPos.x < 0 || nextPos.x >= width || nextPos.y < 0 || nextPos.y>=height)
           {
               overFlow = true;
           }
           if (overFlow)
           {
               return false;
           }
           //检测是否是目标
           if (target.x == nextPos.x&&target.y==nextPos.y)
           {
               results.Add(nextPos);
               return true;
           }
           //不是-1 说明该位置有图片，不能通过
           if (matrix[nextPos.x, nextPos.y]!=-1)
           {
               return false;
           }
           //加入路径
           results.Add(nextPos);
           bool find = false;
           //按照当前方向继续试探
           find = _find(results, chance, direct, target);
           if (find)
           {
               return true;
           }
           //转弯机会已经耗尽
           if (chance <= 0)
           {
               //此路不通，将路径最后一个位置删除
               results.RemoveAt(results.Count - 1);
               return false;
           }
           //当前方向向东，还可以转弯向南，向北继续试探
           if (Direct.East == direct)
           {
               find = _find(results, chance-1, Direct.North, target);
               if (find)
               {
                   return true;
               }
               find = _find(results, chance-1, Direct.South, target);
               if (find)
               {
                   return true;
               }
               results.RemoveAt(results.Count - 1);
               return false;
           }
           //当前方向向南，还可以转弯向东，向西继续试探
           else if (Direct.South == direct)
           {
               find = _find(results, chance-1, Direct.East, target);
               if (find)
               {
                   return true;
               }
               find = _find(results, chance-1, Direct.West, target);
               if (find)
               {
                   return true;
               }
               results.RemoveAt(results.Count - 1);
               return false;
           }
           //当前方向向西，还可以转弯向南，向北继续试探
           else if (Direct.West == direct)
           {
               find = _find(results, chance-1, Direct.North, target);
               if (find)
               {
                   return true;
               }
               find = _find(results, chance-1, Direct.South, target);
               if (find)
               {
                   return true;
               }
               results.RemoveAt(results.Count - 1);
               return false;
           }
           //当前方向向北，还可以转弯向东，向西继续试探
           else
           {
               find = _find(results, chance-1, Direct.East, target);
               if (find)
               {
                   return true;
               }
               find = _find(results, chance-1, Direct.West, target);
               if (find)
               {
                   return true;
               }
               results.RemoveAt(results.Count - 1);
               return false;
           }
       }
       //联通成功后，将两个位置设置成空
       public void onSuccess()
       {
           this.matrix[this.lastPicture.x, this.lastPicture.y] = -1;
           this.matrix[this.currentPicture.x, this.currentPicture.y] = -1;
           this.currentPicture = null;
           this.lastPicture = null;
       }


   }
   
   public class Position
   {
       public int x { get; set; }
       public int y { get; set; }
       //picture 表示不同图像，如果是-1，表示为空
       public int picture { get; set; }
   }

   public enum Direct : int
   {
       East = 0, South = 1, West = 2, North = 3
   }
//csharp/1148