adventofcode-2020/day-8/src/main.rs

50 lines
1.4 KiB
Rust

use std::fs;
mod emulator;
use emulator::{parse_code, Emulator, EmulatorError, Instruction};
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("input")?;
let program = parse_code(&input)?;
// Part 1
let mut emulator = Emulator::new();
if let Err(EmulatorError::InfiniteLoop { accumulator }) =
emulator.run_program_finitely(&program)
{
println!("{}", accumulator);
} else {
panic!("We should get an infinite loop.");
}
// Part 2
let result = program
.iter()
.enumerate()
.filter_map(|(i, instruction)| match instruction {
(Instruction::Jump, arg) => {
let mut program = program.clone();
program[i] = (Instruction::NoOperation, *arg);
emulator.reset();
emulator.run_program_finitely(&program).ok()
}
(Instruction::NoOperation, arg) => {
let mut program = program.clone();
program[i] = (Instruction::Jump, *arg);
emulator.reset();
emulator.run_program_finitely(&program).ok()
}
(_, _) => None,
})
.next();
if let Some(result) = result {
println!("{}", result);
} else {
panic!("We should have at least one non-infinte loop.");
}
Ok(())
}