RosettaCodeData/Task/Last-letter-first-letter/Elixir/last-letter-first-letter.elixir
2016-12-05 22:15:40 +01:00

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1.6 KiB
Text

defmodule LastLetter_FirstLetter do
def search(names) do
first = Enum.group_by(names, &String.first/1)
sequences = Enum.reduce(names, [], fn name,acc -> add_name(first, acc, [name]) end)
max = Enum.max_by(sequences, &length/1) |> length
max_seqs = Enum.filter(sequences, fn seq -> length(seq) == max end)
IO.puts "there are #{length(sequences)} possible sequences"
IO.puts "the longest is #{max} names long"
IO.puts "there are #{length(max_seqs)} such sequences. one is:"
hd(max_seqs) |> Enum.with_index |>
Enum.each(fn {name, idx} ->
:io.fwrite " ~2w ~s~n", [idx+1, name]
end)
end
defp add_name(first, sequences, seq) do
last_letter = String.last(hd(seq))
potentials = Map.get(first, last_letter, []) -- seq
if potentials == [] do
[Enum.reverse(seq) | sequences]
else
Enum.reduce(potentials, sequences, fn name, acc -> add_name(first, acc, [name | seq]) end)
end
end
end
names = ~w(
audino bagon baltoy banette bidoof braviary bronzor carracosta charmeleon
cresselia croagunk darmanitan deino emboar emolga exeggcute gabite
girafarig gulpin haxorus heatmor heatran ivysaur jellicent jumpluff kangaskhan
kricketune landorus ledyba loudred lumineon lunatone machamp magnezone mamoswine
nosepass petilil pidgeotto pikachu pinsir poliwrath poochyena porygon2
porygonz registeel relicanth remoraid rufflet sableye scolipede scrafty seaking
sealeo silcoon simisear snivy snorlax spoink starly tirtouga trapinch treecko
tyrogue vigoroth vulpix wailord wartortle whismur wingull yamask
)
LastLetter_FirstLetter.search(names)