Given a word and a list of possible anagrams, select the correct sublist.
Given "listen"
and a list of candidates like "enlists" "google" "inlets" "banana"
the program should return a list containing
"inlets"
.
Execute the tests with:
$ mix test
In the test suites, all but the first test have been skipped.
Once you get a test passing, you can unskip the next one by
commenting out the relevant @tag :pending
with a #
symbol.
For example:
# @tag :pending
test "shouting" do
assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end
Or, you can enable all the tests by commenting out the
ExUnit.configure
line in the test suite.
# ExUnit.configure exclude: :pending, trace: true
If you're stuck on something, it may help to look at some of the available resources out there where answers might be found.
Inspired by the Extreme Startup game https://github.com/rchatley/extreme_startup
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
defmodule AnagramTest do
use ExUnit.Case
# @tag :pending
test "no matches" do
matches = Anagram.match("diaper", ["hello", "world", "zombies", "pants"])
assert matches == []
end
@tag :pending
test "detect simple anagram" do
matches = Anagram.match("ant", ["tan", "stand", "at"])
assert matches == ["tan"]
end
@tag :pending
test "detect multiple anagrams" do
matches = Anagram.match("master", ["stream", "pigeon", "maters"])
assert matches == ["stream", "maters"]
end
@tag :pending
test "do not detect anagram subsets" do
matches = Anagram.match("good", ~w(dog goody))
assert matches == []
end
@tag :pending
test "detect anagram" do
matches = Anagram.match("listen", ~w(enlists google inlets banana))
assert matches == ["inlets"]
end
@tag :pending
test "multiple anagrams" do
matches = Anagram.match("allergy", ~w(gallery ballerina regally clergy largely leading))
assert matches == ["gallery", "regally", "largely"]
end
@tag :pending
test "anagrams must use all letters exactly once" do
matches = Anagram.match("patter", ["tapper"])
assert matches == []
end
@tag :pending
test "detect anagrams with case-insensitive subject" do
matches = Anagram.match("Orchestra", ~w(cashregister carthorse radishes))
assert matches == ["carthorse"]
end
@tag :pending
test "detect anagrams with case-insensitive candidate" do
matches = Anagram.match("orchestra", ~w(cashregister Carthorse radishes))
assert matches == ["Carthorse"]
end
@tag :pending
test "anagrams must not be the source word" do
matches = Anagram.match("corn", ["corn", "dark", "Corn", "rank", "CORN", "cron", "park"])
assert matches == ["cron"]
end
@tag :pending
test "do not detect words based on checksum" do
matches = Anagram.match("mass", ["last"])
assert matches == []
end
end
ExUnit.start()
ExUnit.configure(exclude: :pending, trace: true)
defmodule Anagram do
@spec match(String.t(), [String.t()]) :: [String.t()]
def match(base, candidates) do
candidates
|> Enum.reduce([], fn candidate, matches ->
candidate
|> anagram?(base)
|> case do
true -> [candidate | matches]
false -> matches
end
end)
|> Enum.reverse()
end
defp anagram?(base, candidate) do
base_letters = base |> String.downcase() |> String.codepoints()
candidate_letters = candidate |> String.downcase() |> String.codepoints()
cond do
base_letters == candidate_letters -> false
length(base_letters) != length(candidate_letters) -> false
true -> Enum.sort(base_letters) == Enum.sort(candidate_letters)
end
end
end
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