Software Sauna Code Challenge

Follow a path of characters & collect letters:

Start at the character @
Follow the path
Collect letters
Stop when you reach the character x

Assignment

Write a piece of code that takes a map of characters as an input and outputs the collected letters and the list of characters of the travelled path.

Input:

a map (2-dimensional array) of characters in a data format of your choice (can even be hard-coded as a global constant)

Output:

Collected letters
Path as characters

What we are looking for in the solution

readable code
- small methods/functions/classes
- good naming
- minimise code duplication
- separation of logic and scaffolding (e.g. walking around is separated from loading the map)
automated tests
- high-level tests (i.e. acceptance tests) which test that the program gives correct output for a given input, according to examples specified below
- unit tests which test small bits of logic separated from the rest of the program, e.g. advancing the current location based on the current direction

About testing

At Software Sauna automated tests are a first-class citizen. This is why we encourage you to try writing some tests, even if you're not accustomed to doing so. An easy win is to start with the example maps provided.

Specifications

Valid maps

A basic example

  @---A---+
          |
  x-B-+   C
      |   |
      +---+

Expected result:

Letters ACB
Path as characters @---A---+|C|+---+|+-B-x

Go straight through intersections

  @
  | +-C--+
  A |    |
  +---B--+
    |      x
    |      |
    +---D--+

Expected result:

Letters ABCD
Path as characters @|A+---B--+|+--C-+|-||+---D--+|x

Letters may be found on turns

  @---A---+
          |
  x-B-+   |
      |   |
      +---C

Expected result:

Letters ACB
Path as characters @---A---+|||C---+|+-B-x

Do not collect a letter from the same location twice

     +-O-N-+
     |     |
     |   +-I-+
 @-G-O-+ | | |
     | | +-+ E
     +-+     S
             |
             x

Expected result:

Letters GOONIES
Path as characters @-G-O-+|+-+|O||+-O-N-+|I|+-+|+-I-+|ES|x

Keep direction, even in a compact space

 +-L-+
 |  +A-+
@B+ ++ H
 ++    x

Expected result:

Letters BLAH
Path as characters @B+++B|+-L-+A+++A-+Hx

Ignore stuff after end of path

  @-A--+
       |
       +-B--x-C--D

Expected result:

Letters AB
Path as characters @-A--+|+-B--x

Invalid maps

Missing start character

     -A---+
          |
  x-B-+   C
      |   |
      +---+

Expected result: Error

Missing end character

   @--A---+
          |
    B-+   C
      |   |
      +---+

Expected result: Error

Multiple starts

   @--A-@-+
          |
  x-B-+   C
      |   |
      +---+

   @--A---+
          |
          C
          x
      @-B-+

   @--A--x

  x-B-+
      |
      @

Expected result: Error

Fork in path

        x-B
          |
   @--A---+
          |
     x+   C
      |   |
      +---+

Expected result: Error

Broken path

   @--A-+
        |
         
        B-x

Expected result: Error

Multiple starting paths

  x-B-@-A-x

Expected result: Error

Fake turn

  @-A-+-B-x

Expected result: Error

Notes

the only valid characters are all uppercase letters (A-Z) and other characters appearing in the example maps; anything else found must result in an error
turns can be letters or +
input examples are jagged matrices - rows (lines) don't contain the same number of elements (characters): this is a valid form of input so keep that in mind