96 lines
2.2 KiB
Elixir
96 lines
2.2 KiB
Elixir
defmodule Day7 do
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def part1 do
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[0, 1, 2, 3, 4]
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|> permutations()
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|> Enum.map(fn digits -> {digits, test_inputs(digits)} end)
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|> Enum.max_by(fn {_, out} -> out end)
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end
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def part2 do
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[5, 6, 7, 8, 9]
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|> permutations()
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|> Enum.map(&test_looped/1)
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|> Enum.max()
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end
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def test_inputs(digits) do
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Enum.reduce(digits, 0, fn phase_setting, prev_output ->
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phase_setting
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|> start_amplifier()
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|> amplifier_step(prev_output)
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end)
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end
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def permutations([]), do: [[]]
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def permutations(list) do
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for x <- list, y <- permutations(list -- [x]), do: [x | y]
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end
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def test_looped(digits) do
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digits
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|> Enum.map(&start_amplifier/1)
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# |> IO.inspect()
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|> Stream.cycle()
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|> Enum.reduce_while(0, fn pid, prev_output ->
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case amplifier_step(pid, prev_output) do
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:halt ->
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{:halt, prev_output}
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output ->
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{:cont, output}
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end
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end)
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end
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def start_amplifier(phase_setting) do
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program = File.read!("lib/day7/input.txt") |> String.trim()
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# part 1 examples:
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# program = "3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0"
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# program = "3,23,3,24,1002,24,10,24,1002,23,-1,23,101,5,23,23,1,24,23,23,4,23,99,0,0"
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# program =
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# "3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0"
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# part 2 examples:
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# program =
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# "3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5"
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# program =
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# "3,52,1001,52,-5,52,3,53,1,52,56,54,1007,54,5,55,1005,55,26,1001,54,-5,54,1105,1,12,1,53,54,53,1008,54,0,55,1001,55,1,55,2,53,55,53,4,53,1001,56,-1,56,1005,56,6,99,0,0,0,0,10"
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program =
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program
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|> String.split(",")
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|> Enum.map(&String.to_integer/1)
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parent = self()
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pid =
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spawn(fn ->
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Day5.run(program, parent)
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end)
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receive do
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{:in, ^pid} -> send(pid, {:in, phase_setting})
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end
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pid
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end
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def amplifier_step(pid, prev_output) do
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receive do
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{:in, ^pid} ->
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send(pid, {:in, prev_output})
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receive do
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{:out, ^pid, val} ->
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val
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{:halt, ^pid} ->
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:halt
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end
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{:halt, ^pid} ->
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:halt
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end
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end
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end
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