133 lines
3.5 KiB
Rust
133 lines
3.5 KiB
Rust
#![feature(test, str_split_once)]
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extern crate test;
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use std::env;
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#[derive(Debug, PartialEq)]
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enum Command {
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NOP(i32),
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ACC(i32),
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JMP(i32),
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}
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fn read_input() -> String {
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std::fs::read_to_string(env::args().nth(1).filter(|n| n != "--bench").unwrap_or(String::from("inputs/day08"))).unwrap()
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}
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fn parse_input(raw: &str) -> Vec<Command> {
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raw.lines()
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.map(|l| match l.split_once(' ') {
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Some(("nop", x)) => Command::NOP(x.parse().unwrap()),
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Some(("acc", x)) => Command::ACC(x.parse().unwrap()),
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Some(("jmp", x)) => Command::JMP(x.parse().unwrap()),
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_ => unreachable!(),
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})
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.collect()
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}
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fn main() {
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let commands = parse_input(&read_input());
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println!("Part 1: {}", part1(&commands));
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println!("Part 2: {}", part2(&commands, vec![false; commands.len()], 0, 0, false).unwrap());
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}
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fn part1(commands: &Vec<Command>) -> i32 {
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let mut seen = vec![false; commands.len()];
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let mut index = 0i32;
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let mut acc = 0;
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loop {
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if seen[index as usize] {
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return acc;
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}
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seen[index as usize] = true;
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match commands[index as usize] {
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Command::NOP(_) => index += 1,
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Command::ACC(x) => {
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acc += x;
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index += 1
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}
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Command::JMP(x) => index += x,
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}
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}
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}
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fn part2(commands: &Vec<Command>, mut seen: Vec<bool>, mut index: i32, mut acc: i32, changed: bool) -> Option<i32> {
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loop {
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if index as usize >= commands.len() {
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return Some(acc);
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}
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if seen[index as usize] {
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return None;
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}
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seen[index as usize] = true;
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match commands[index as usize] {
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Command::NOP(x) => {
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if !changed {
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if let Some(n) = part2(commands, seen.clone(), index + x, acc, true) {
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return Some(n);
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}
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}
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index += 1;
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}
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Command::ACC(x) => {
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acc += x;
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index += 1
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}
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Command::JMP(x) => {
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// is there no way to have regular if and if let in one statement?
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if !changed {
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if let Some(n) = part2(commands, seen.clone(), index + 1, acc, true) {
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return Some(n);
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}
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}
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index += x;
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}
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use test::black_box;
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const TEST_INPUT: &str = "nop +0
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acc +1
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jmp +4
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acc +3
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jmp -3
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acc -99
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acc +1
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jmp -4
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acc +6";
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#[test]
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fn part1_test() {
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let commands = parse_input(TEST_INPUT);
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assert_eq!(part1(&commands), 5);
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}
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#[test]
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fn part2_test() {
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let commands = parse_input(TEST_INPUT);
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assert_eq!(part2(&commands, vec![false; commands.len()], 0, 0, false), Some(8));
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}
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#[bench]
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fn bench_part1(b: &mut test::Bencher) {
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let commands = parse_input(&read_input());
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b.iter(|| assert_eq!(part1(black_box(&commands)), 1317));
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}
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#[bench]
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fn bench_part2(b: &mut test::Bencher) {
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let commands = parse_input(&read_input());
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b.iter(|| assert_eq!(part2(black_box(&commands), vec![false; commands.len()], 0, 0, false), Some(1033)));
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}
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#[bench]
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fn bench_input_parsing(b: &mut test::Bencher) {
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let raw = read_input();
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b.iter(|| assert_eq!(parse_input(black_box(&raw)).len(), 626))
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}
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}
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