Ruby Quizzes

Several coding exercises, short and mostly proposed by others.

Table of contents

• The exercises
• Running and benchmarking solutions
  • Examples
• Tests

The exercises

Each exercise is in its own folder under exercises/, and usually consist in three different files:

• README.md: the exercise instructions, in Markdown format. What it has to be done.
• test_data.rb: some constants to run the solution and benchmarks:
  • TEST_DATA: Some test data for benchmarking. Hash with the shape input => expected output.
  • METHODS_MULTIPLE_ARITY : A Hash with the name(s) of the method(s) that do the work, as keys, and as a value, a boolean, whether the solution method takes one or several arguments.
  • PARAM_TRANSFORMATION: as I will invoke the exercise from the command line (see below run_solution.rb), this is a lambda to transform an String argument (from the command line) into the class of the solution method argument (for example, a String '[1, 2, 3]' into the Array [1, 2, 3]).
• solution.rb, or similar (solution_1.rb, ...): a solution to the exercise. If you want to do the exercise, don't look here yet.

We could have more than one solution. There is an executable to run some performance benchmarks (see below).

Running and benchmarking solutions

These are two Ruby executables at the root of this repository:

• run_solution.rb: passing the exercise folder and an input value, tries to execute the exercise. If more than one is present, or the file is not called solution.rb, the file name with the solution can be passed as a third parameter.
• compare_solutions.rb: passing the exercise folder, looks for solutions of the form solution*.rb (solution_1.rb, solution_2.rb, ...), and runs some benchmarks.

For run_solution.rb, the parameter to use would be a single String, so the exercise tries to convert it to the data expected

Examples

./run_solution.rb 1_number_format 1000
  For '1000', the solution is '1,000'

./run_solution.rb 2_anagram maple solution
  For 'maple', the solution is '["ample", "maple"]'

./run_solution.rb 7_caesar_cipher_variation 'lalalalala,1' encode_str            
  For '["lalalalala", 1]', the solution is '["lmm", "bmb", "mbm", "bmb"]'

./run_solution.rb 7_caesar_cipher_variation '["lmm", "bmb", "mbm", "bmb"]' decode 
  For '["lmm", "bmb", "mbm", "bmb"]', the solution is 'lalalalala'

In the case of compare_solutions.rb, I only have one solution at this moment:

./compare_solutions.rb 3_binary_periods

  Benchmarks for '3_binary_periods':

  Rehearsal ---------------------------------------------
  solution:   0.000023   0.000001   0.000024 (  0.000023)
  ------------------------------------ total: 0.000024sec

                  user     system      total        real
  solution:   0.000021   0.000001   0.000022 (  0.000021)

But for some exercises I used to have several alternative solutions (you can see them by going back through the Git history):

./compare_solutions.rb 3_binary_periods

  Benchmarks for '3_binary_periods':

  Rehearsal -----------------------------------------------
  solution_1:   0.000221   0.000017   0.000238 (  0.000237)
  solution_2:   0.000677   0.000018   0.000695 (  0.000694)
  solution_3:   0.000031   0.000001   0.000032 (  0.000031)
  solution_4:   0.000022   0.000001   0.000023 (  0.000022)
  -------------------------------------- total: 0.000988sec

                    user     system      total        real
  solution_1:   0.000211   0.000004   0.000215 (  0.000214)
  solution_2:   0.000228   0.000012   0.000240 (  0.000241)
  solution_3:   0.000028   0.000010   0.000038 (  0.000039)
  solution_4:   0.000022   0.000000   0.000022 (  0.000022)

Tests

It uses Minitest with the Specs DSL. Run bundle to set it up.

To run all the specs, run rake:

rake
  Run options: --seed 33218

  # Running:

  ..........

  Finished in 0.110904s, 90.1681 runs/s, 919.7143 assertions/s.

  10 runs, 102 assertions, 0 failures, 0 errors, 0 skips

The tests can also be run independently, for each exercise:

rake test TEST=spec/7_caesar_cipher_variation_spec.rb
  Run options: --seed 37685

  # Running:

  ..

  Finished in 0.000713s, 2805.0488 runs/s, 26647.9636 assertions/s.

  2 runs, 19 assertions, 0 failures, 0 errors, 0 skips

See the exercises' specs under the spec/ folder`.