johannes/advent-of-rust-2024
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added grid utility and used it to speed up day 6

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Johannes
2024-12-06 15:33:57 +01:00
parent 476f34e2b4
commit 2636f4a6c8
4 changed files with 124 additions and 16 deletions
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29
src/day06.rs
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@@ -3,6 +3,8 @@ use std::{
fs::read_to_string,
};
use crate::utils::grid::Grid;
pub fn day_main() {
let input = read_to_string("input/day06.txt").unwrap();
let input = input.trim();
@@ -11,7 +13,7 @@ pub fn day_main() {
}
type RiddleResult = usize;
type Point = (i32, i32);
type Point = (i64, i64);
fn part1(input: &str) -> RiddleResult {
let (m, pos) = parse(input);
@@ -21,13 +23,9 @@ fn part1(input: &str) -> RiddleResult {
visited.len()
}
fn get_visited(
m: &HashMap<(i32, i32), char>,
mut pos: (i32, i32),
mut dir: char,
) -> HashSet<(i32, i32)> {
fn get_visited(m: &Grid<char>, mut pos: Point, mut dir: char) -> HashSet<Point> {
let mut visited = HashSet::new();
while m.contains_key(&pos) {
while m.contains_key(pos) {
let (x, y) = pos;
visited.insert(pos);
let next = match dir {
@@ -37,7 +35,7 @@ fn get_visited(
'>' => (x + 1, y),
_ => unreachable!(),
};
if let Some('#') = m.get(&next) {
if m.contains_key(next) && '#' == m[next] {
dir = match dir {
'^' => '>',
'v' => '<',
@@ -62,13 +60,13 @@ fn part2(input: &str) -> RiddleResult {
.count()
}
fn parse(input: &str) -> (HashMap<Point, char>, Point) {
fn parse(input: &str) -> (Grid<char>, Point) {
let mut m = HashMap::new();
let mut pos = None;
input.lines().enumerate().for_each(|(y, line)| {
line.char_indices().for_each(|(x, c)| {
let x = x as i32;
let y = y as i32;
let x = x as i64;
let y = y as i64;
if c == '^' {
pos = Some((x, y));
m.insert((x, y), '.');
@@ -77,10 +75,10 @@ fn parse(input: &str) -> (HashMap<Point, char>, Point) {
}
});
});
(m, pos.unwrap())
(Grid::from(m), pos.unwrap())
}
fn is_loop(m: &HashMap<Point, char>, block: Point, mut pos: Point, mut dir: char) -> bool {
fn is_loop(m: &Grid<char>, block: Point, mut pos: Point, mut dir: char) -> bool {
let mut visited = HashSet::new();
loop {
let (x, y) = pos;
@@ -92,10 +90,9 @@ fn is_loop(m: &HashMap<Point, char>, block: Point, mut pos: Point, mut dir: char
'>' => (x + 1, y),
_ => unreachable!(),
};
let next_tile = m.get(&next);
if None == next_tile {
if !m.contains_key(next) {
return false;
} else if next == block || Some(&'#') == next_tile {
} else if next == block || '#' == m[next] {
// we only check for loops on a collision to speed things up
if visited.contains(&(pos, dir)) {
return true;