115 lines
2.8 KiB
Rust
115 lines
2.8 KiB
Rust
#![feature(test)]
|
|
#![allow(clippy::ptr_arg, clippy::upper_case_acronyms)]
|
|
extern crate test;
|
|
use aoc2020::common::*;
|
|
|
|
#[derive(Debug, PartialEq)]
|
|
enum Command {
|
|
NOP(i32),
|
|
ACC(i32),
|
|
JMP(i32),
|
|
}
|
|
|
|
fn read_input() -> String {
|
|
read_file(8)
|
|
}
|
|
|
|
fn parse_input(raw: &str) -> Vec<Command> {
|
|
raw.lines()
|
|
.map(|l| match l.split_once(' ') {
|
|
Some(("nop", x)) => Command::NOP(x.parse().unwrap()),
|
|
Some(("acc", x)) => Command::ACC(x.parse().unwrap()),
|
|
Some(("jmp", x)) => Command::JMP(x.parse().unwrap()),
|
|
_ => unreachable!(),
|
|
})
|
|
.collect()
|
|
}
|
|
|
|
fn main() {
|
|
let commands = parse_input(&read_input());
|
|
println!("Part 1: {}", part1(&commands));
|
|
println!(
|
|
"Part 2: {}",
|
|
part2(&commands, &mut vec![false; commands.len()], 0, 0, false).unwrap()
|
|
);
|
|
}
|
|
|
|
fn part1(commands: &Vec<Command>) -> i32 {
|
|
let mut seen = vec![false; commands.len()];
|
|
let mut index = 0i32;
|
|
let mut acc = 0;
|
|
loop {
|
|
if seen[index as usize] {
|
|
return acc;
|
|
}
|
|
seen[index as usize] = true;
|
|
match commands[index as usize] {
|
|
Command::NOP(_) => index += 1,
|
|
Command::ACC(x) => {
|
|
acc += x;
|
|
index += 1
|
|
}
|
|
Command::JMP(x) => index += x,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn part2(commands: &Vec<Command>, seen: &mut Vec<bool>, mut index: i32, mut acc: i32, changed: bool) -> Option<i32> {
|
|
loop {
|
|
if index as usize >= commands.len() {
|
|
return Some(acc);
|
|
}
|
|
if changed && seen[index as usize] {
|
|
return None;
|
|
}
|
|
seen[index as usize] = true;
|
|
match commands[index as usize] {
|
|
Command::NOP(x) => {
|
|
if !changed && index > -x {
|
|
if let Some(n) = part2(commands, seen, index + x, acc, true) {
|
|
return Some(n);
|
|
}
|
|
}
|
|
index += 1;
|
|
}
|
|
Command::ACC(x) => {
|
|
acc += x;
|
|
index += 1
|
|
}
|
|
Command::JMP(x) => {
|
|
// is there no way to have regular if and if let in one statement?
|
|
if !changed {
|
|
if let Some(n) = part2(commands, seen, index + 1, acc, true) {
|
|
return Some(n);
|
|
}
|
|
}
|
|
index += x;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
use test::black_box;
|
|
use aoc2020::*;
|
|
use paste::paste;
|
|
|
|
const TEST_INPUT: &str = "nop +0
|
|
acc +1
|
|
jmp +4
|
|
acc +3
|
|
jmp -3
|
|
acc -99
|
|
acc +1
|
|
jmp -4
|
|
acc +6";
|
|
|
|
test!(part1() == 5);
|
|
test!(part2(&mut vec![false; 9], 0, 0, false) == Some(8));
|
|
bench!(part1() == 1317);
|
|
bench!(part2(&mut vec![false; 626], 0, 0, false) == Some(1033));
|
|
bench_input!(len == 626);
|
|
}
|