AdventOfCode2022/09/main.rs

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6.7 KiB
Rust
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2022-12-17 22:08:09 +00:00
#![allow(dead_code)]
use std::collections::HashMap;
use std::fs::File;
use std::io;
use std::io::BufRead;
use std::path::Path;
use std::time::Instant;
#[derive(Debug, Eq, Hash, PartialEq, Copy, Clone)]
struct Coord(i32, i32);
fn main() {
let now = Instant::now();
part_one();
let part_one_duration = now.elapsed();
part_two();
let part_two_duration = now.elapsed();
println!(
"p1: {}ms, p2: {}ms",
part_one_duration.as_millis(),
(part_two_duration - part_one_duration).as_millis()
);
}
fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
where
P: AsRef<Path>,
{
// note that this discards a final newline
let file = File::open(filename)?;
Ok(io::BufReader::new(file).lines())
}
fn part_one() {
let mut grid = HashMap::<Coord, bool>::new();
let (mut head_x, mut head_y) = (0, 0);
let (mut tail_x, mut tail_y) = (0, 0);
grid.insert(Coord(0, 0), true);
if let Ok(lines) = read_lines("./inputs/input") {
for line in lines {
if let Ok(m) = line {
let mut i = m.split(" ");
let dir = i.next().unwrap();
let steps = i.next().unwrap().parse::<i32>().unwrap();
match dir {
"U" => {
for _ in 0..steps {
head_y += 1;
(tail_x, tail_y) = update_tail(head_x, head_y, tail_x, tail_y);
grid.insert(Coord(tail_x, tail_y), true);
}
}
"D" => {
for _ in 0..steps {
head_y -= 1;
(tail_x, tail_y) = update_tail(head_x, head_y, tail_x, tail_y);
grid.insert(Coord(tail_x, tail_y), true);
}
}
"L" => {
for _ in 0..steps {
head_x -= 1;
(tail_x, tail_y) = update_tail(head_x, head_y, tail_x, tail_y);
grid.insert(Coord(tail_x, tail_y), true);
}
}
"R" => {
for _ in 0..steps {
head_x += 1;
(tail_x, tail_y) = update_tail(head_x, head_y, tail_x, tail_y);
grid.insert(Coord(tail_x, tail_y), true);
}
}
_ => {
println!("unknown instruction {:?}", m);
}
}
}
}
}
println!("{}", grid.len());
}
fn part_two() {
let mut grid = HashMap::<Coord, bool>::new();
let mut knots: Vec<Coord> = vec![
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
Coord(0, 0),
];
if let Ok(lines) = read_lines("./inputs/input") {
for line in lines {
if let Ok(m) = line {
let mut i = m.split(" ");
let dir = i.next().unwrap();
let steps = i.next().unwrap().parse::<i32>().unwrap();
match dir {
"U" => {
for _ in 0..steps {
knots[0] = Coord(knots[0].0, knots[0].1 + 1);
for j in 0..9 {
let (tail_x, tail_y) = update_tail(
knots[j].0,
knots[j].1,
knots[j + 1].0,
knots[j + 1].1,
);
knots[j + 1] = Coord(tail_x, tail_y);
}
grid.insert(knots[9], true);
}
}
"D" => {
for _ in 0..steps {
knots[0] = Coord(knots[0].0, knots[0].1 - 1);
for j in 0..9 {
let (tail_x, tail_y) = update_tail(
knots[j].0,
knots[j].1,
knots[j + 1].0,
knots[j + 1].1,
);
knots[j + 1] = Coord(tail_x, tail_y);
}
grid.insert(knots[9], true);
}
}
"L" => {
for _ in 0..steps {
knots[0] = Coord(knots[0].0 - 1, knots[0].1);
for j in 0..9 {
let (tail_x, tail_y) = update_tail(
knots[j].0,
knots[j].1,
knots[j + 1].0,
knots[j + 1].1,
);
knots[j + 1] = Coord(tail_x, tail_y);
}
grid.insert(knots[9], true);
}
}
"R" => {
for _ in 0..steps {
knots[0] = Coord(knots[0].0 + 1, knots[0].1);
for j in 0..9 {
let (tail_x, tail_y) = update_tail(
knots[j].0,
knots[j].1,
knots[j + 1].0,
knots[j + 1].1,
);
knots[j + 1] = Coord(tail_x, tail_y);
}
grid.insert(knots[9], true);
}
}
_ => {
println!("unknown instruction {:?}", m);
}
}
}
}
}
println!("{}", grid.len());
}
fn update_tail(head_x: i32, head_y: i32, mut tail_x: i32, mut tail_y: i32) -> (i32, i32) {
if head_y - tail_y == 2 {
tail_y += 1;
tail_x = head_x;
}
if tail_y - head_y == 2 {
tail_y -= 1;
tail_x = head_x;
}
if head_x - tail_x == 2 {
tail_x += 1;
tail_y = head_y;
}
if tail_x - head_x == 2 {
tail_x -= 1;
tail_y = head_y;
}
return (tail_x, tail_y);
}