45 lines
1.1 KiB
Elixir
45 lines
1.1 KiB
Elixir
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defmodule School do
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@moduledoc """
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Simulate students in a school.
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Each student is in a grade.
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"""
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@type school :: any()
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@doc """
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Create a new, empty school.
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"""
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@spec new() :: school
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def new(), do: %{}
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@doc """
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Add a student to a particular grade in school.
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"""
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@spec add(school, String.t(), integer) :: {:ok | :error, school}
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def add(school, name, grade) do
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if Enum.any?(roster(school), &(&1 == name)) do
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{:error, school}
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else
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{:ok, Map.put(school, grade, [name | Map.get(school, grade, [])])}
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end
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end
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@doc """
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Return the names of the students in a particular grade, sorted alphabetically.
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"""
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@spec grade(school, integer) :: [String.t()]
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def grade(school, grade) when not is_map_key(school, grade), do: []
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def grade(school, grade), do: Enum.sort(Map.get(school, grade))
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@doc """
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Return the names of all the students in the school sorted by grade and name.
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"""
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@spec roster(school) :: [String.t()]
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def roster(school) do
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for grade <- Enum.sort(Map.keys(school)), reduce: [] do
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acc -> acc ++ grade(school, grade)
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end
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end
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end
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