private int[] IterateOnSpiral(int[,] matrix)
    {
        var pairs = this.GeneratePairsCollection(matrix.GetLength(0), matrix.GetLength(1));
        var direction = Directions.Right;
        int i = 0, j = 0, resultsIter = 0;
        var result = new int[matrix.Length];

        while (pairs.Any())
        {
            result[resultIter++] = matrix[i, j];
            pairs.Remove(new Tuple<int, int>(i, j));

            if (direction == Directions.Right)
            {
                if (pairs.Contains(new Tuple<int, int>(i, j + 1)))
                {
                    j++;
                }
                else
                {
                    directions = Directions.Down;
                }
            }
        }
    }

    private ISet<Tuple<int, int>> GeneratePairsCollection(int m, int n)
    {
        var result = new HashSet<Tuple<int, int>>();

        for (var i = 0; i < matrix.GetLength(0); i++)
        {
            for (var j = 0; j < matrix.GetLength(1); j++)
            {
                result.Add(new Tuple<int, int>(i, j));
            }
        }

       return result;
    }

    private enum Directions
    {
        Right, Left, Up, Down
    }
}