This commit is contained in:
Dory 2024-03-11 23:57:48 -07:00
parent bfdd227743
commit 017345beb6
3 changed files with 77 additions and 20 deletions

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@ -6,34 +6,44 @@ use std::collections::HashSet;
fn main() {
let file = File::open(&env::args().nth(1).unwrap()).unwrap();
let reader = io::BufReader::new(file);
let (mut hx, mut hy, mut tx, mut ty) = (0, 0, 0, 0);
let mut rope: [(i64, i64); 10] = [(0, 0); 10];
let mut visited: HashSet<(i64, i64)> = vec![(0, 0)].into_iter().collect();
for line in reader.lines().flatten() {
let (movx, movy) = match line.chars().nth(0) {
Some('L') => (-1, 0),
Some('R') => (1, 0),
Some('U') => (0, -1),
Some('D') => (0, 1),
_ => (999, 999),
};
let count = line[2..].parse::<i64>().unwrap();
let ((movx, movy), count) = parse_line(line).unwrap();
for _ in 0..count {
(hx, hy) = (hx + movx, hy + movy);
(tx, ty) = move_tail(hx, hy, tx, ty).unwrap();
visited.insert((tx, ty));
rope[0] = (rope[0].0 + movx, rope[0].1 + movy);
for link in 1..=9 {
rope[link] = move_tail(rope[link - 1], rope[link]);
}
visited.insert(rope[9]);
}
}
println!("{:?}", visited.len());
}
fn move_tail(hx: i64, hy: i64, tx: i64, ty: i64) -> Option<(i64, i64)> {
match (hx - tx, hy - ty) {
(-1..=1, -1..=1) => Some((tx, ty)),
(-1..=1, 2) => Some((hx, ty + 1)),
(-1..=1, -2) => Some((hx, ty - 1)),
(2, -1..=1) => Some((tx + 1, hy)),
(-2, -1..=1) => Some((tx - 1, hy)),
_ => None
fn parse_line(line: String) -> Option<((i64, i64), i64)> {
let mov = match line.chars().nth(0) {
Some('L') => Some((-1, 0)),
Some('R') => Some((1, 0)),
Some('U') => Some((0, -1)),
Some('D') => Some((0, 1)),
_ => None,
};
let count = line[2..].parse::<i64>();
match (mov, count) {
(Some(mov), Ok(count)) => Some((mov, count)),
_ => None,
}
}
fn move_tail((hx, hy): (i64, i64), (tx, ty): (i64, i64)) -> (i64, i64) {
let dx = if hx > tx { 1 } else { -1 };
let dy = if hy > ty { 1 } else { -1 };
match (hx - tx, hy - ty) {
(-1..=1, -1..=1) => (tx, ty),
(-1..=1, _) => (hx, ty + dy),
(_, -1..=1) => (tx + dx, hy),
(_, _) => (tx + dx, ty + dy),
}
}

39
day9/src/main1.rs Normal file
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@ -0,0 +1,39 @@
use std::env;
use std::fs::File;
use std::io::{self, BufRead};
use std::collections::HashSet;
fn main() {
let file = File::open(&env::args().nth(1).unwrap()).unwrap();
let reader = io::BufReader::new(file);
let (mut hx, mut hy, mut tx, mut ty) = (0, 0, 0, 0);
let mut visited: HashSet<(i64, i64)> = vec![(0, 0)].into_iter().collect();
for line in reader.lines().flatten() {
let (movx, movy) = match line.chars().nth(0) {
Some('L') => (-1, 0),
Some('R') => (1, 0),
Some('U') => (0, -1),
Some('D') => (0, 1),
_ => (999, 999),
};
let count = line[2..].parse::<i64>().unwrap();
for _ in 0..count {
(hx, hy) = (hx + movx, hy + movy);
(tx, ty) = move_tail(hx, hy, tx, ty).unwrap();
visited.insert((tx, ty));
}
}
println!("{:?}", visited.len());
}
fn move_tail(hx: i64, hy: i64, tx: i64, ty: i64) -> Option<(i64, i64)> {
match (hx - tx, hy - ty) {
(-1..=1, -1..=1) => Some((tx, ty)),
(-1..=1, 2) => Some((hx, ty + 1)),
(-1..=1, -2) => Some((hx, ty - 1)),
(2, -1..=1) => Some((tx + 1, hy)),
(-2, -1..=1) => Some((tx - 1, hy)),
_ => None
}
}

8
day9/test2.txt Normal file
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@ -0,0 +1,8 @@
R 5
U 8
L 8
D 3
R 17
D 10
L 25
U 20