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day14 solution

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Andrew Coleman 2023-12-24 16:49:31 -05:00
parent 765e0d90cf
commit 95003d0b0a
2 changed files with 215 additions and 0 deletions

214
2023/src/day14.rs Normal file
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@ -0,0 +1,214 @@
use aoc_runner_derive::{aoc, aoc_generator};
use std::collections::HashSet;
#[aoc_generator(day14)]
fn parse(input: &str) -> Vec<String> {
input
.lines()
.filter_map(|line| {
if !line.is_empty() {
Some(String::from(line))
} else {
None
}
})
.collect::<Vec<_>>()
}
fn map_to_string(map: &[[char; 100]; 100]) -> String {
let mut s = String::with_capacity(100 * 100);
for row in map.iter() {
let mut has_char = false;
for &c in row.iter() {
if c == ' ' {
break;
}
has_char = true;
s.push(c);
}
if has_char {
s.push('\n');
}
}
s
}
fn score(input: &str) -> usize {
let lines = input
.split("\n")
.filter_map(|t| {
if t.is_empty() {
None
} else {
Some(String::from(t))
}
})
.collect::<Vec<String>>();
let mut score = 0;
let total_lines = lines.len();
for (index, line) in lines.iter().enumerate() {
score += line.matches("O").collect::<Vec<_>>().len() * (total_lines - index);
}
score
}
#[aoc(day14, part1)]
fn part1(input: &[String]) -> usize {
let mut map: [[char; 100]; 100] = [[' '; 100]; 100];
for (row, line) in input.iter().enumerate() {
for (col, c) in line.chars().enumerate() {
map[row][col] = c;
}
}
tilt_north(&mut map);
score(&map_to_string(&map))
}
fn tilt_north(map: &mut [[char; 100]; 100]) -> String {
for col in 0..(map[0]).len() {
let mut r = 0;
for row in (0..(map.len())).rev() {
if map[row][col] == ' ' {
continue;
} else if map[row][col] == '#' {
for rock in 1..=r {
map[row + rock][col] = 'O';
}
r = 0;
} else if map[row][col] == 'O' {
r += 1;
map[row][col] = '.';
}
}
for rock in 1..=r {
map[rock - 1][col] = 'O';
}
}
map_to_string(&map)
}
fn tilt_west(map: &mut [[char; 100]; 100]) -> String {
for row in 0..map.len() {
let mut r = 0;
for col in (0..map[0].len()).rev() {
if map[row][col] == ' ' {
continue;
} else if map[row][col] == '#' {
for rock in 1..=r {
map[row][col + rock] = 'O';
}
r = 0;
} else if map[row][col] == 'O' {
r += 1;
map[row][col] = '.';
}
}
for rock in 1..=r {
map[row][rock - 1] = 'O';
}
}
map_to_string(&map)
}
fn tilt_south(map: &mut [[char; 100]; 100]) -> String {
for col in 0..map[0].len() {
let mut r = 0;
let mut last_row = 100;
for row in 0..map.len() {
if map[row][col] == ' ' {
last_row = row;
break;
} else if map[row][col] == '#' {
for rock in 1..=r {
map[row - rock][col] = 'O';
}
r = 0;
} else if map[row][col] == 'O' {
r += 1;
map[row][col] = '.';
}
}
for rock in 1..=r {
map[last_row - rock][col] = 'O';
}
}
map_to_string(&map)
}
fn tilt_east(map: &mut [[char; 100]; 100]) -> String {
for row in 0..map.len() {
let mut r = 0;
let mut last_col = 100;
for col in 0..map[row].len() {
if map[row][col] == ' ' {
last_col = col;
break;
} else if map[row][col] == '#' {
for rock in 1..=r {
map[row][col - rock] = 'O';
}
r = 0;
} else if map[row][col] == 'O' {
r += 1;
map[row][col] = '.';
}
}
for rock in 1..=r {
map[row][last_col - rock] = 'O';
}
}
map_to_string(&map)
}
#[aoc(day14, part2)]
fn part2(input: &[String]) -> usize {
let mut map: [[char; 100]; 100] = [[' '; 100]; 100];
for (row, line) in input.iter().enumerate() {
for (col, c) in line.chars().enumerate() {
map[row][col] = c;
}
}
let mut patterns: HashSet<String> = HashSet::new();
let mut seq: Vec<String> = vec![];
let mut iters = 0;
loop {
if iters == 1000 {
break;
}
tilt_north(&mut map);
tilt_west(&mut map);
tilt_south(&mut map);
tilt_east(&mut map);
let s = map_to_string(&map);
iters += 1;
seq.push(s.clone());
patterns.insert(s);
}
let score = score(&seq[999]);
score
}
#[cfg(test)]
mod tests {
use super::*;
const SAMPLE_DATA: &'static str = r#"O....#....
O.OO#....#
.....##...
OO.#O....O
.O.....O#.
O.#..O.#.#
..O..#O..O
.......O..
#....###..
#OO..#....
"#;
#[test]
fn sample_data() {
let input = parse(&SAMPLE_DATA);
assert_eq!(part1(&input), 136);
assert_eq!(part2(&input), 64);
}
}

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@ -13,5 +13,6 @@ mod day10;
mod day11; mod day11;
mod day12; mod day12;
mod day13; mod day13;
mod day14;
aoc_lib! { year = 2023 } aoc_lib! { year = 2023 }