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Practice Exercises in Exercism v3 will be structured differently. One such change is that there won't be a (generated) README.md file anymore. This file will be replaced by `.docs/instructions.md` and optionally a `.docs/introduction.md` files. These files are copies of the information defined for their corresponding problem-specifications exercise (if any). Exercism v3 will build the README.md file that is sent via the CLI from these files contents, along with some other files. See [this document](https://github.com/exercism/docs/blob/main/anatomy/tracks/presentation.md) for more information. To add track-specific contents to the instructions and/or introduction, exercises can define the (optional) `introduction.append.md` and `instructions.append.md` files. If present, the contents of these files will automatically be append to their corresponding file when generating the README.md See [the spec](https://github.com/exercism/docs/blob/main/anatomy/tracks/practice-exercises.md) for more information.
Simple Linked List
Write a simple linked list implementation that uses Elements and a List.
The linked list is a fundamental data structure in computer science, often used in the implementation of other data structures. They're pervasive in functional programming languages, such as Clojure, Erlang, or Haskell, but far less common in imperative languages such as Ruby or Python.
The simplest kind of linked list is a singly linked list. Each element in the list contains data and a "next" field pointing to the next element in the list of elements.
This variant of linked lists is often used to represent sequences or push-down stacks (also called a LIFO stack; Last In, First Out).
As a first take, lets create a singly linked list to contain the range (1..10), and provide functions to reverse a linked list and convert to and from arrays.
When implementing this in a language with built-in linked lists, implement your own abstract data type.
Hints
To support list(), see implementing an iterator for a class.
Additionally, note that Python2's next() has been replaced by __next__() in Python3. For dual compatibility, next() can be implemented as:
def next(self):
return self.__next__()
Exception messages
Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include a message.
To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
raise Exception, you should write:
raise Exception("Meaningful message indicating the source of the error")
Running the tests
To run the tests, run pytest simple_linked_list_test.py
Alternatively, you can tell Python to run the pytest module:
python -m pytest simple_linked_list_test.py
Common pytest options
-v: enable verbose output-x: stop running tests on first failure--ff: run failures from previous test before running other test cases
For other options, see python -m pytest -h
Submitting Exercises
Note that, when trying to submit an exercise, make sure the solution is in the $EXERCISM_WORKSPACE/python/simple-linked-list directory.
You can find your Exercism workspace by running exercism debug and looking for the line that starts with Workspace.
For more detailed information about running tests, code style and linting, please see Running the Tests.
Source
Inspired by 'Data Structures and Algorithms with Object-Oriented Design Patterns in Ruby', singly linked-lists. http://www.brpreiss.com/books/opus8/html/page96.html#SECTION004300000000000000000
Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.