If you want to build something using a Raspberry Pi, you'll probably use resistors. For this exercise, you need to know two things about them:
In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands. The program will take color names as input and output a two digit number, even if the input is more than two colors!
The colors are mapped to the numbers from 0 to 9 in the sequence: Black - Brown - Red - Orange - Yellow - Green - Blue - Violet - Grey - White
From the example above: brown-green should return 15 brown-green-violet should return 15 too, ignoring the third color.
For installation and learning resources, refer to the Ruby resources page.
For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:
gem install minitest
If you would like color output, you can require 'minitest/pride'
in
the test file, or note the alternative instruction, below, for running
the test file.
Run the tests from the exercise directory using the following command:
ruby resistor_color_duo_test.rb
To include color from the command line:
ruby -r minitest/pride resistor_color_duo_test.rb
Maud de Vries, Erik Schierboom https://github.com/exercism/problem-specifications/issues/1464
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
require 'minitest/autorun'
require_relative 'resistor_color_duo'
# Common test data version: 2.1.0 00dda3a
class ResistorColorDuoTest < Minitest::Test
def test_brown_and_black
# skip
assert_equal 10, ResistorColorDuo.value(["brown", "black"])
end
def test_blue_and_grey
skip
assert_equal 68, ResistorColorDuo.value(["blue", "grey"])
end
def test_yellow_and_violet
skip
assert_equal 47, ResistorColorDuo.value(["yellow", "violet"])
end
def test_orange_and_orange
skip
assert_equal 33, ResistorColorDuo.value(["orange", "orange"])
end
def test_ignore_additional_colors
skip
assert_equal 51, ResistorColorDuo.value(["green", "brown", "orange"])
end
end
# In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands. The program will take color names as input and output a two digit number, even if the input is more than two colors!
# The colors are mapped to the numbers from 0 to 9 in the sequence:
# Black - Brown - Red - Orange - Yellow - Green - Blue - Violet - Grey - White
# From the example above:
# brown-green should return 15
# brown-green-violet should return 15 too, ignoring the third color.
class ResistorColorDuo
DIGITS = {
'black' => 0,
'brown' => 1,
'red' => 2,
'orange' => 3,
'yellow' => 4,
'green' => 5,
'blue' => 6,
'violet' => 7,
'grey' => 8,
'white' => 9
}.freeze
def self.value (colors=[])
Integer(DIGITS.values_at(colors[0], colors[1]).join)
end
end
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.
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