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use aoc2019::*;
use std::io;
use std::io::prelude::*;
use std::process;
use structopt::StructOpt;
#[derive(Debug, StructOpt)]
#[structopt(name = "Day 2: 1202 Program Alarm")]
/// Executes an Intcode program
///
/// The program is read from stdin as a series of comma-separated
/// values. Newlines are ignored. When the program halts, the value at
/// position 0 is returned.
///
/// If an output is provided, all possible inputs are tried to find
/// the input that results in the desired output. In this case, the
/// inputs are returned in the format (noun, verb).
///
///See https://adventofcode.com/2019/day/2 for details.
struct Opt {
#[structopt(short = "n", long = "noun")]
noun: Option<Intcode>,
#[structopt(short = "v", long = "verb")]
verb: Option<Intcode>,
#[structopt(short = "o", long = "output")]
output: Option<Intcode>,
}
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();
match (opt.noun, opt.verb, opt.output) {
(Some(noun), Some(verb), _) => {
let result = exit_on_failed_assertion(
program
.with_noun_verb_input(noun, verb)
.execute_returning_memory_0(),
"Program errored",
);
println!("{}", result);
}
(_, _, Some(output)) => {
let (noun, verb) =
exit_on_failed_assertion(find_input(&program, output), "Program errored");
println!("({}, {})", noun, verb);
}
(None, None, None) => {
let result =
exit_on_failed_assertion(program.execute_returning_memory_0(), "Program errored");
println!("{}", result);
}
_ => {
eprintln!("Either a noun and verb or an expected output must be provided");
process::exit(1);
}
}
}
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_input(
program: &IntcodeProgram,
output: Intcode,
) -> Result<(Intcode, Intcode), IntcodeProgramError> {
(0..99)
.flat_map(|noun| (0..99).map(move |verb| (Intcode::from(noun), Intcode::from(verb))))
.map(|(noun, verb)| {
(
noun.clone(),
verb.clone(),
program
.with_noun_verb_input(noun, verb)
.execute_returning_memory_0(),
)
})
.find(|(_noun, _verb, out)| *out == Ok(output.clone()))
.map(|(noun, verb, _out)| Ok((noun, verb)))
.unwrap_or(Err(IntcodeProgramError::Unknown))
}
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