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mryan's solution

to Raindrops in the Raku Track

Published at Apr 21 2021 · 0 comments
Instructions
Test suite
Solution

Your task is to convert a number into a string that contains raindrop sounds corresponding to certain potential factors. A factor is a number that evenly divides into another number, leaving no remainder. The simplest way to test if a one number is a factor of another is to use the modulo operation.

The rules of raindrops are that if a given number:

  • has 3 as a factor, add 'Pling' to the result.
  • has 5 as a factor, add 'Plang' to the result.
  • has 7 as a factor, add 'Plong' to the result.
  • does not have any of 3, 5, or 7 as a factor, the result should be the digits of the number.

Examples

  • 28 has 7 as a factor, but not 3 or 5, so the result would be "Plong".
  • 30 has both 3 and 5 as factors, but not 7, so the result would be "PlingPlang".
  • 34 is not factored by 3, 5, or 7, so the result would be "34".

Resources

Remember to check out the Raku documentation and resources pages for information, tips, and examples if you get stuck.

Running the tests

There is a test suite and module included with the exercise. The test suite (a file with the extension .rakutest) will attempt to run routines from the module (a file with the extension .rakumod). Add/modify routines in the module so that the tests will pass! You can view the test data by executing the command raku --doc *.rakutest (* being the name of the test suite), and run the test suite for the exercise by executing the command prove6 . in the exercise directory.

Source

A variation on FizzBuzz, a famous technical interview question that is intended to weed out potential candidates. That question is itself derived from Fizz Buzz, a popular children's game for teaching division. https://en.wikipedia.org/wiki/Fizz_buzz

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

raindrops.rakutest

#!/usr/bin/env raku
use Test;
use JSON::Fast;
use lib $?FILE.IO.dirname;
use Raindrops;
plan 18;

my @test-cases = from-json($=pod.pop.contents).List;
for @test-cases -> %case {
  subtest %case<description>, {
    plan 2;
    isa-ok ( my $result := raindrop %case<input><number> ), Str;
    is $result, %case<expected>, 'Result matches expected';
  }
}

=head2 Test Cases
=begin code
[
  {
    "description": "the sound for 1 is 1",
    "expected": "1",
    "input": {
      "number": 1
    },
    "property": "convert"
  },
  {
    "description": "the sound for 3 is Pling",
    "expected": "Pling",
    "input": {
      "number": 3
    },
    "property": "convert"
  },
  {
    "description": "the sound for 5 is Plang",
    "expected": "Plang",
    "input": {
      "number": 5
    },
    "property": "convert"
  },
  {
    "description": "the sound for 7 is Plong",
    "expected": "Plong",
    "input": {
      "number": 7
    },
    "property": "convert"
  },
  {
    "description": "the sound for 6 is Pling as it has a factor 3",
    "expected": "Pling",
    "input": {
      "number": 6
    },
    "property": "convert"
  },
  {
    "description": "2 to the power 3 does not make a raindrop sound as 3 is the exponent not the base",
    "expected": "8",
    "input": {
      "number": 8
    },
    "property": "convert"
  },
  {
    "description": "the sound for 9 is Pling as it has a factor 3",
    "expected": "Pling",
    "input": {
      "number": 9
    },
    "property": "convert"
  },
  {
    "description": "the sound for 10 is Plang as it has a factor 5",
    "expected": "Plang",
    "input": {
      "number": 10
    },
    "property": "convert"
  },
  {
    "description": "the sound for 14 is Plong as it has a factor of 7",
    "expected": "Plong",
    "input": {
      "number": 14
    },
    "property": "convert"
  },
  {
    "description": "the sound for 15 is PlingPlang as it has factors 3 and 5",
    "expected": "PlingPlang",
    "input": {
      "number": 15
    },
    "property": "convert"
  },
  {
    "description": "the sound for 21 is PlingPlong as it has factors 3 and 7",
    "expected": "PlingPlong",
    "input": {
      "number": 21
    },
    "property": "convert"
  },
  {
    "description": "the sound for 25 is Plang as it has a factor 5",
    "expected": "Plang",
    "input": {
      "number": 25
    },
    "property": "convert"
  },
  {
    "description": "the sound for 27 is Pling as it has a factor 3",
    "expected": "Pling",
    "input": {
      "number": 27
    },
    "property": "convert"
  },
  {
    "description": "the sound for 35 is PlangPlong as it has factors 5 and 7",
    "expected": "PlangPlong",
    "input": {
      "number": 35
    },
    "property": "convert"
  },
  {
    "description": "the sound for 49 is Plong as it has a factor 7",
    "expected": "Plong",
    "input": {
      "number": 49
    },
    "property": "convert"
  },
  {
    "description": "the sound for 52 is 52",
    "expected": "52",
    "input": {
      "number": 52
    },
    "property": "convert"
  },
  {
    "description": "the sound for 105 is PlingPlangPlong as it has factors 3, 5 and 7",
    "expected": "PlingPlangPlong",
    "input": {
      "number": 105
    },
    "property": "convert"
  },
  {
    "description": "the sound for 3125 is Plang as it has a factor 5",
    "expected": "Plang",
    "input": {
      "number": 3125
    },
    "property": "convert"
  }
]
=end code
unit module Raindrops:ver<1>;

sub raindrop (Int $num) is export {
    my $sound ;
	$sound ~= "Pling" if $num %% 3 ;
	$sound ~= "Plang" if $num %% 5 ;
	$sound ~= "Plong" if $num %% 7 ;
    return $sound // $num.Str
}

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