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use aoc2019::*;
use rpds::list;
use rpds::list::List;
use rpds::vector::Vector;
use std::io;
use std::io::prelude::*;
use std::iter;
use std::process;
use structopt::StructOpt;
#[derive(Debug, StructOpt)]
#[structopt(name = "Day 7: Amplification Circuit")]
/// Executes an Intcode program on 5 amplifiers, and finds the input that gives the max output
///
/// See https://adventofcode.com/2019/day/7 for details.
struct Opt {
#[structopt(short = "f", long = "feedback-loop")]
feedback_loop_mode: bool,
}
fn main() {
let stdin = io::stdin();
let opt = Opt::from_args();
let program: IntcodeProgram = stdin
.lock()
.split(b',')
.map(|x| exit_on_failed_assertion(x, "Error reading input"))
.map(|x| exit_on_failed_assertion(String::from_utf8(x), "Input was not valid UTF-8"))
.map(|x| exit_on_failed_assertion(x.trim().parse::<Intcode>(), "Invalid number"))
.collect::<IntcodeProgram>();
let result = exit_on_failed_assertion(
find_max_power(&program, opt.feedback_loop_mode),
"Program errored",
);
println!("{}", result);
}
fn exit_on_failed_assertion<A, E: std::error::Error>(data: Result<A, E>, message: &str) -> A {
match data {
Ok(data) => data,
Err(e) => {
eprintln!("{}: {}", message, e);
process::exit(1);
}
}
}
fn find_max_power(
program: &IntcodeProgram,
feedback_loop_mode: bool,
) -> Result<Intcode, IntcodeProgramError> {
PhaseSetting::all(feedback_loop_mode)
.map(|phase| AmplifierArray::new(program, &phase).execute())
.collect::<Result<Vec<Intcode>, _>>()
.map(|powers| powers.into_iter().max().unwrap_or(Intcode::from(0)))
}
#[derive(Debug, Clone)]
struct PhaseSetting([Intcode; 5]);
impl PhaseSetting {
fn all(feedback_loop_mode: bool) -> impl Iterator<Item = PhaseSetting> {
if feedback_loop_mode {
PhaseSetting::permute(5, 10)
} else {
PhaseSetting::permute(0, 5)
}
}
fn permute(min: i32, max: i32) -> impl Iterator<Item = PhaseSetting> {
// This is an absolutely atrocious way to do the permutation,
// but luckily it's only 5 elements long.
(min..max)
.flat_map(move |a| {
(min..max).flat_map(move |b| {
(min..max).flat_map(move |c| {
(min..max).flat_map(move |d| {
(min..max).map(move |e| {
PhaseSetting([a.into(), b.into(), c.into(), d.into(), e.into()])
})
})
})
})
})
.filter(move |phase| (min..max).all(|x| phase.0.contains(&x.into())))
}
}
#[derive(Debug, Clone)]
struct AmplifierArray {
amplifiers: Vector<IntcodeProgram>,
}
impl AmplifierArray {
fn new(program: &IntcodeProgram, phase: &PhaseSetting) -> AmplifierArray {
AmplifierArray {
amplifiers: (0..5)
.map(|n| AmplifierArray::new_amp(program, phase, n))
.collect(),
}
}
fn new_amp(program: &IntcodeProgram, phase: &PhaseSetting, n: usize) -> IntcodeProgram {
if n == 0 {
program.with_input(list![phase.0[n].clone(), Intcode::from(0)])
} else {
program.with_input(list![phase.0[n].clone()])
}
}
fn execute(&self) -> Result<Intcode, IntcodeProgramError> {
self.run_to_termination().output_into_result()
}
fn run_to_termination(&self) -> AmplifierArray {
iter::successors(Some(self.clone()), |p| Some(p.next()))
.find(|p| p.is_terminated())
.unwrap() // successors doesn't terminate, so this will never be none.
}
fn output_into_result(&self) -> Result<Intcode, IntcodeProgramError> {
self.amplifiers
.first()
.and_then(|amp| amp.input.first().cloned())
.ok_or(IntcodeProgramError::Unknown)
}
fn is_terminated(&self) -> bool {
self.amplifiers.last().map(|amp| amp.halted).unwrap_or(true)
}
fn next(&self) -> AmplifierArray {
self.run_amplifiers().update_inputs()
}
fn run_amplifiers(&self) -> AmplifierArray {
AmplifierArray {
amplifiers: self
.amplifiers
.iter()
.map(|amp| amp.run_to_termination_or_input())
.collect(),
}
}
fn update_inputs(&self) -> AmplifierArray {
AmplifierArray {
amplifiers: self
.amplifiers
.iter()
.fold(
(
Vector::new(),
self.amplifiers
.last()
.map(|a| a.output.iter().cloned().collect::<List<Intcode>>())
.unwrap_or(List::new()),
),
|(amps, piped_input), next_amp| {
(
amps.push_back(
next_amp
.with_additional_input(piped_input)
.with_cleared_output(),
),
next_amp.output.iter().cloned().collect::<List<Intcode>>(),
)
},
)
.0,
}
}
}
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