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use std::collections::HashMap;
use crate::{Problem, Solution};
pub struct Day14;
impl Problem for Day14 {
const DAY: u8 = 14;
const INPUT: &'static str = include_str!("../input/day_14.txt");
}
impl Solution for Day14 {
type Answer1 = usize;
type Answer2 = usize;
fn part_1(input: &str) -> anyhow::Result<Self::Answer1> {
let mut grid = input
.lines()
.map(|s| s.chars().collect::<Vec<_>>())
.collect::<Vec<_>>();
print_grid(&grid);
tilt_grid(&mut grid);
print_grid(&grid);
Ok(grid_load(grid))
}
fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
let grid = input
.lines()
.map(|s| s.chars().collect::<Vec<_>>())
.collect::<Vec<_>>();
Ok(process_grid(grid, 1000000000))
// 105606 ==
}
}
type Grid = Vec<Vec<char>>;
fn process_grid(mut grid: Grid, count: usize) -> usize {
let mut cache = HashMap::new();
for i in 0..=count {
for _ in 0..4 {
tilt_grid(&mut grid);
grid = rotate_grid(&grid);
}
if let Some(cycle) = cache.insert(grid.clone(), i).map(|n| n + 1) {
println!("\rcycle found: {cycle} - {i}");
return process_grid(grid, count % (i - cycle));
}
}
print_grid(&grid);
grid_load(grid)
}
fn print_grid(grid: &Grid) {
println!(
"{}\n",
grid.iter()
.map(|v| v.iter().collect::<String>())
.collect::<Vec<_>>()
.join("\n")
)
}
fn tilt_grid(grid: &mut Grid) {
for col in 0..grid[0].len() {
for mut row in 0..grid.len() {
if grid[row][col] == 'O' {
grid[row][col] = '.';
while row > 0 && grid[row - 1][col] == '.' {
row -= 1;
}
grid[row][col] = 'O';
}
}
}
}
fn rotate_grid(grid: &Grid) -> Vec<Vec<char>> {
let mut rot: Vec<Vec<char>> = vec![vec!['.'; grid.len()]; grid[0].len()];
for (col, v) in rot.iter_mut().enumerate() {
for (row, c) in v.iter_mut().rev().enumerate() {
*c = grid[row][col];
}
}
rot
}
fn grid_load(grid: Grid) -> usize {
grid.iter()
.rev()
.enumerate()
.map(|(row, v)| {
v.iter()
.filter(|&&c| c == 'O')
.map(|_| row + 1)
.sum::<usize>()
})
.sum()
}
#[cfg(test)]
mod tests {
use super::*;
const INPUT: &str = indoc::indoc! {"
O....#....
O.OO#....#
.....##...
OO.#O....O
.O.....O#.
O.#..O.#.#
..O..#O..O
.......O..
#....###..
#OO..#....
"};
#[test]
fn test_part_1() -> anyhow::Result<()> {
Ok(assert_eq!(136, Day14::part_1(INPUT)?))
}
#[test]
fn test_part_2() -> anyhow::Result<()> {
Ok(assert_eq!(64, Day14::part_2(INPUT)?))
}
}
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