AoC19/lib/day7/day7.ex

119 lines
2.6 KiB
Elixir

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