65 lines
2.7 KiB
Elixir
65 lines
2.7 KiB
Elixir
defmodule DaySeven do
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def part_one(input) do
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deps = parse_input(input)
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letters = Enum.map(?A..?Z, &(<<&1>>))
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Enum.reverse resolve_instructions(deps, letters, [])
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end
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def part_two(input) do
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deps = parse_input(input)
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letters = Enum.map(?A..?Z, &(<<&1>>))
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resolve_workers(deps, letters, [], 5, 0) - 1
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end
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def parse_input(input) do
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regex = ~r/Step (\w) must be finished before step (\w) can begin\./
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String.split(input, "\n")
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|> Enum.filter(&(&1 != ""))
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|> Enum.map(fn line ->
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[[_, on, dep]] = Regex.scan(regex, line)
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{on, dep}
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end)
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end
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def resolve_instructions([], [ letter ], acc), do: [letter | acc ]
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def resolve_instructions(deps, remletters, acc) do
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firsts = Enum.filter(remletters, fn letter -> not Enum.member?(Enum.map(deps, fn {_on, dep} -> dep end), letter) end)
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[first | _ ] = firsts |> Enum.sort
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rem = Enum.filter(deps, fn {on, _dep} -> on != first end)
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rletters = Enum.filter(remletters, fn letter -> letter != first end)
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resolve_instructions(rem, rletters, [first | acc])
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end
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def resolve_workers(_deps, [], _workers, _, acc), do: acc
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def resolve_workers(deps, remletters, workers, maxworkers, acc) do
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sworkers = Enum.map(workers, fn {task, time} -> {task, time - 1} end)
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step_workers = Enum.filter(sworkers, fn {_, time} -> time != 0 end)
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completed = Enum.filter(sworkers, fn {_, time} -> time == 0 end)
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|> Enum.map(fn {task, _} -> task end)
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uremletters = Enum.filter(remletters, &(not Enum.member?(completed, &1)))
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udeps = Enum.filter(deps, fn {on, _dep} -> not Enum.member?(completed, on) end)
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canwork = Enum.filter(uremletters, fn letter -> not Enum.member?(Enum.map(udeps, fn {_on, dep} -> dep end), letter) end) |> Enum.filter(fn letter -> not Enum.member?(Enum.map(step_workers, fn {task, _} -> task end), letter) end)
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uworkers = if length(step_workers) < maxworkers and length(canwork) > 0 do
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schedule_work(canwork, maxworkers - length(step_workers), step_workers)
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else
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step_workers
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end
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# IO.puts "Move #{acc}, now working on #{Enum.map(uworkers, fn {task, time} -> "(#{task}: #{time})" end) |> Enum.join(", ")}"
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resolve_workers(udeps, uremletters, uworkers, maxworkers, acc + 1)
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end
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def schedule_work([], _, workers), do: workers
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def schedule_work(_, 0, workers), do: workers
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def schedule_work([work | tail], numworkers, workers) do
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schedule_work(tail, numworkers - 1, [{work, time_taken(work)} | workers])
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end
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def time_taken(<< letter >>), do: letter - 4
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end
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{:ok, content} = File.read("input7.txt")
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IO.puts("Part 1: #{DaySeven.part_one(content)}")
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IO.puts("Part 2: #{DaySeven.part_two(content)}")
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