75 lines
2.5 KiB
Markdown
75 lines
2.5 KiB
Markdown
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# Resistor Color Trio
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Welcome to Resistor Color Trio on Exercism's Elixir Track.
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If you need help running the tests or submitting your code, check out `HELP.md`.
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## Instructions
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If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
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For this exercise, you need to know only three things about them:
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- Each resistor has a resistance value.
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- Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.
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To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values.
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- Each band acts as a digit of a number.
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For example, if they printed a brown band (value 1) followed by a green band (value 5), it would translate to the number 15.
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In this exercise, you are going to create a helpful program so that you don't have to remember the values of the bands.
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The program will take 3 colors as input, and outputs the correct value, in ohms.
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The color bands are encoded as follows:
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- black: 0
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- brown: 1
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- red: 2
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- orange: 3
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- yellow: 4
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- green: 5
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- blue: 6
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- violet: 7
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- grey: 8
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- white: 9
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In Resistor Color Duo you decoded the first two colors.
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For instance: orange-orange got the main value `33`.
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The third color stands for how many zeros need to be added to the main value.
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The main value plus the zeros gives us a value in ohms.
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For the exercise it doesn't matter what ohms really are.
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For example:
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- orange-orange-black would be 33 and no zeros, which becomes 33 ohms.
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- orange-orange-red would be 33 and 2 zeros, which becomes 3300 ohms.
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- orange-orange-orange would be 33 and 3 zeros, which becomes 33000 ohms.
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(If Math is your thing, you may want to think of the zeros as exponents of 10.
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If Math is not your thing, go with the zeros.
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It really is the same thing, just in plain English instead of Math lingo.)
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This exercise is about translating the colors into a label:
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> "... ohms"
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So an input of `"orange", "orange", "black"` should return:
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> "33 ohms"
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When we get to larger resistors, a [metric prefix][metric-prefix] is used to indicate a larger magnitude of ohms, such as "kiloohms".
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That is similar to saying "2 kilometers" instead of "2000 meters", or "2 kilograms" for "2000 grams".
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For example, an input of `"orange", "orange", "orange"` should return:
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> "33 kiloohms"
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[metric-prefix]: https://en.wikipedia.org/wiki/Metric_prefix
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## Source
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### Created by
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- @jiegillet
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### Contributed to by
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- @angelikatyborska
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### Based on
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Maud de Vries, Erik Schierboom - https://github.com/exercism/problem-specifications/issues/1549
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