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day14_2.rs
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day14_2.rs
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use std::{fmt::Display, str::FromStr};
#[derive(Debug, Clone, Copy, PartialEq)]
enum Item {
Rock,
SandSource,
Air,
Sand,
}
#[derive(Debug, PartialEq)]
struct Coord {
x: usize,
y: usize,
}
#[derive(Debug)]
struct Cave {
grid: Vec<Vec<Item>>,
size_x: usize,
size_y: usize,
sand_source: Coord,
}
impl FromStr for Coord {
type Err = ();
fn from_str(s: &str) -> Result<Self, Self::Err> {
let (x_str, y_str) = s.split_once(",").unwrap();
Ok(Self {
x: x_str.parse().unwrap(),
y: y_str.parse().unwrap(),
})
}
}
impl Display for Cave {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let mut s = String::new();
for row in &self.grid {
for col in row {
match col {
Item::Rock => s += "# ",
Item::SandSource => s += "+ ",
Item::Air => s += ". ",
Item::Sand => s += "o ",
}
}
s += "\n"
}
write!(f, "{}", s)
}
}
const FLOOR_EXPANSION_SIZE: usize = 10;
impl Cave {
fn new(size_x: usize, size_y: usize, sand_x: usize, sand_y: usize) -> Self {
let grid: Vec<Vec<Item>> = vec![vec![Item::Air; size_x]; size_y];
Self {
grid,
size_x,
size_y,
sand_source: Coord {
x: sand_x,
y: sand_y,
},
}
}
fn expand_floor(&mut self) {
for (i, row) in self.grid.iter_mut().enumerate() {
let item = if i == self.size_y - 1 {
Item::Rock
} else {
Item::Air
};
row.splice(0..0, vec![item; FLOOR_EXPANSION_SIZE / 2]);
row.splice(row.len().., vec![item; FLOOR_EXPANSION_SIZE / 2]);
}
}
fn fill(&mut self, lines: &Vec<Vec<Coord>>) {
for line in lines {
let mut coords = line.iter();
let mut curr = coords.next();
while let Some(c) = curr {
self.grid[c.y][c.x] = Item::Rock;
if let Some(next) = coords.next() {
curr = Some(next);
if c.x == next.x {
if c.y < next.y {
for y in c.y + 1..next.y + 1 {
self.grid[y][c.x] = Item::Rock;
}
} else {
for y in next.y..c.y + 1 {
self.grid[y][c.x] = Item::Rock;
}
}
} else if c.y == next.y {
if c.x < next.x {
for x in c.x + 1..next.x + 1 {
self.grid[c.y][x] = Item::Rock;
}
} else {
for x in next.x..c.x + 1 {
self.grid[c.y][x] = Item::Rock;
}
}
}
} else {
break;
}
}
}
for x in 0..self.size_x {
self.grid[self.size_y - 1][x] = Item::Rock;
}
self.grid[self.sand_source.y][self.sand_source.x] = Item::SandSource;
}
fn produce_sand(&mut self) -> bool {
let mut sand_coord = Coord {
x: self.sand_source.x,
y: self.sand_source.y,
};
loop {
if self.grid[sand_coord.y + 1][sand_coord.x] == Item::Air {
sand_coord.y += 1;
} else if self.grid[sand_coord.y + 1][sand_coord.x - 1] == Item::Air {
sand_coord.y += 1;
sand_coord.x -= 1;
} else if self.grid[sand_coord.y + 1][sand_coord.x + 1] == Item::Air {
sand_coord.y += 1;
sand_coord.x += 1;
} else {
self.grid[sand_coord.y][sand_coord.x] = Item::Sand;
if sand_coord == self.sand_source {
return true;
}
break;
}
if sand_coord.y + 1 == self.size_y {
break;
}
if sand_coord.x + 1 == self.size_x || sand_coord.x == 0 {
self.expand_floor();
self.sand_source.x += FLOOR_EXPANSION_SIZE / 2;
sand_coord.x += FLOOR_EXPANSION_SIZE / 2;
}
}
false
}
}
fn main() {
let input = include_str!("../inputs/day14.txt");
let lines: Vec<Vec<Coord>> = input
.lines()
.map(|l| {
l.split(" -> ")
.map(|s| s.parse::<Coord>().unwrap())
.collect()
})
.collect();
let min_x: usize = lines.iter().flatten().map(|c| c.x).min().unwrap();
let max_y: usize = lines.iter().flatten().map(|c| c.y).max().unwrap();
let normalized_lines: Vec<Vec<Coord>> = lines
.iter()
.map(|l| {
l.iter()
.map(|c| Coord {
x: c.x - min_x,
y: c.y,
})
.collect()
})
.collect();
let max_x: usize = normalized_lines
.iter()
.flatten()
.map(|c| c.x)
.max()
.unwrap();
let mut cave: Cave = Cave::new(max_x + 1, max_y + 3, 500 - min_x, 0);
cave.fill(&normalized_lines);
let mut rested = 1;
loop {
let voided = cave.produce_sand();
if voided {
break;
}
rested += 1;
}
println!("{}", rested);
}