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July 10, 2013 09:50
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The Prime Factors Kata implemented in elixir
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defmodule PrimeFactors do | |
@moduledoc """ | |
Inspired by Uncle Bob's algorithm: | |
http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata | |
""" | |
@doc """ | |
Функция generate/1 получает целое число в качестве параметра | |
и возвращает все простые делители этого числа в виде списка. | |
""" | |
@spec generate(integer) :: list | |
def generate(n) do | |
generate(n, [], 2) |> Enum.sort | |
end | |
# The inner "while" cicle | |
defp generate(n, prime_factors, candidate) when rem(n, candidate) == 0 do | |
generate(div(n, candidate), [candidate|prime_factors], candidate) | |
end | |
# The outer "while" cicle | |
defp generate(n, prime_factors, candidate) when n > 1 do | |
generate(n, prime_factors, candidate + 1) | |
end | |
defp generate(_n, prime_factors, _candidate), do: prime_factors | |
end | |
ExUnit.start | |
defmodule PrimeFactorsTest do | |
use ExUnit.Case, async: true | |
test "generates all prime factors of a given number" do | |
Enum.each [ [[2], 2], | |
[[3], 3], | |
[[2,2], 4], | |
[[5], 5], | |
[[2,3], 6], | |
[[7], 7], | |
[[2,2,2], 8], | |
[[3,3], 9], | |
[[2,5], 10], | |
[[11], 11], | |
[[2,2,3], 12], | |
[[13], 13] | |
], fn [prime_factors, number] -> | |
assert prime_factors == PrimeFactors.generate(number) | |
end | |
end | |
end |
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It looks great! Very similar to Uncle Bob code. I like how you mark the methods private. I have to learn to do that. I also like how you did the sort. That is really cool. Does the code return it in descending order, is that why you have to sort it? I haven't started on mine. I've been super busy. Hopefully soon :)