defmodule Day7 do def part1 do [0, 1, 2, 3, 4] |> permutations() |> Enum.map(fn digits -> {digits, test_inputs(digits)} end) |> Enum.max_by(fn {_, out} -> out end) end def part2 do [5, 6, 7, 8, 9] |> permutations() |> Enum.map(&test_looped/1) |> Enum.max() end def test_inputs(digits) do Enum.reduce(digits, 0, &run_amplifier/2) end def run_amplifier(phase_setting, prev_output) do program = File.read!("lib/day7/input.txt") |> String.trim() # program = "3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0" # 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" # program = # "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" program = program |> String.split(",") |> Enum.map(&String.to_integer/1) parent = self() pid = spawn(fn -> Day5.run(program, parent) end) receive do {:in, ^pid} -> send(pid, {:in, phase_setting}) end receive do {:in, ^pid} -> send(pid, {:in, prev_output}) end receive do {:out, ^pid, val} -> val end end def permutations([]), do: [[]] def permutations(list) do for x <- list, y <- permutations(list -- [x]), do: [x | y] end def test_looped(digits) do digits |> Enum.map(&start_amplifier/1) # |> IO.inspect() |> Stream.cycle() |> Enum.reduce_while(0, fn pid, prev_output -> case amplifier_step(pid, prev_output) do :halt -> {:halt, prev_output} output -> {:cont, output} end end) end def start_amplifier(phase_setting) do program = File.read!("lib/day7/input.txt") |> String.trim() # program = # "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" # program = # "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" program = program |> String.split(",") |> Enum.map(&String.to_integer/1) parent = self() pid = spawn(fn -> Day5.run(program, parent) end) receive do {:in, ^pid} -> send(pid, {:in, phase_setting}) end pid end def amplifier_step(pid, prev_output) do receive do {:in, ^pid} -> send(pid, {:in, prev_output}) receive do {:out, ^pid, val} -> val {:halt, ^pid} -> :halt end {:halt, ^pid} -> :halt end end end