private void QueueUp(PrioriQ Q, int[,] lot, HashSet <int[]> visited, int[] pair, int cost)
 {
     if (lot[pair[0], pair[1]] != 0 && !visited.Contains(pair))
     {
         Q.Enqueue(new Item(pair[0], pair[1], cost));
     }
 }
        public int removeObs(int r, int c, int[,] lot)
        {
            if (r <= 0 || c <= 0 || lot == null)
            {
                return(-1);
            }

            PrioriQ         Q       = new PrioriQ();
            HashSet <int[]> visited = new HashSet <int[]>();

            //0,0 is always flat
            Q.Enqueue(new Item(0, 0, 0));
            while (Q.Count > 0)
            {
                Item item = Q.Dequeue();
                //if(visited.Contains()
                int[] pair = new int[2];
                pair[0] = item.Row;
                pair[1] = item.Col;
                if (visited.Contains(pair))
                {
                    continue;
                }
                if (lot[pair[0], pair[1]] == 9)
                {
                    return(item.Length);
                }
                visited.Add(pair);
                if (item.Row > 0)
                {
                    QueueUp(Q, lot, visited, new int[] { pair[0] - 1, pair[1] }, item.Length + 1);
                }
                if (item.Row < r - 1)
                {
                    QueueUp(Q, lot, visited, new int[] { pair[0] + 1, pair[1] }, item.Length + 1);
                }
                if (item.Col > 0)
                {
                    QueueUp(Q, lot, visited, new int[] { pair[0], pair[1] - 1 }, item.Length + 1);
                }
                if (item.Col < c - 1)
                {
                    QueueUp(Q, lot, visited, new int[] { pair[0], pair[1] + 1 }, item.Length + 1);
                }
            }

            return(-1);
        }