part 1 solution
parent
4834780347
commit
dfcdf0f83d
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@ -3,18 +3,34 @@ use std::fs::File;
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use std::io::{BufRead, BufReader};
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use std::ops::Range;
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const MapSize: usize = 1800;
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type Map = [[char; MapSize]; MapSize];
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const MAP_SIZE: usize = 1800;
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const FOUNTAIN: char = '+';
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const EMPTY_SPACE: char = ' ';
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const WALL_SPACE: char = '#';
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const WATER: char = '~';
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const FALLING_WATER: char = '|';
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type Map = Vec<Vec<char>>;
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fn find_range_in_line(line: &str) -> (Range<u16>, Range<u16>) {
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#[derive(Debug, PartialEq)]
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struct Coord {
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x: usize,
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y: usize,
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}
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struct MapBounds {
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min_y: usize,
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max_y: usize,
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}
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fn find_range_in_line(line: &str) -> (Range<usize>, Range<usize>) {
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let mut parts = line.split(", ");
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let mut left_parts = parts.nth(0).unwrap().split("=");
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let left_coord_type: &str = left_parts.nth(0).unwrap();
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let left_number: u16 = left_parts.nth(0).unwrap().parse().unwrap();
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let left_number: usize = left_parts.nth(0).unwrap().parse().unwrap();
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let mut right_parts = parts.nth(0).unwrap().split("=");
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let mut right_numbers = right_parts.nth(1).unwrap().split("..");
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let right_number_1: u16 = right_numbers.nth(0).unwrap().parse().unwrap();
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let right_number_2: u16 = right_numbers.nth(0).unwrap().parse().unwrap();
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let right_number_1: usize = right_numbers.nth(0).unwrap().parse().unwrap();
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let right_number_2: usize = right_numbers.nth(0).unwrap().parse().unwrap();
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let left_range = Range { start: left_number, end: left_number + 1 };
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let right_range = Range { start: right_number_1, end: right_number_2 + 1 };
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if left_coord_type == "x" {
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@ -24,22 +40,169 @@ fn find_range_in_line(line: &str) -> (Range<u16>, Range<u16>) {
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}
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}
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fn build_map_from_file(filename: &str) -> Map {
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fn print_map(map: &Map, min_x: usize, max_x: usize, min_y: usize, max_y: usize) {
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for y in min_y..=max_y {
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for x in min_x..=max_x {
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print!("{}", map[x][y]);
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}
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println!();
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}
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}
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fn build_map_from_file(filename: &str) -> (Map, MapBounds) {
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let mut min_y: usize = MAP_SIZE;
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let mut max_y: usize = 0;
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let mut m = Vec::<Vec<char>>::with_capacity(MAP_SIZE);
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for _ in 0..MAP_SIZE {
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let mut n = Vec::<char>::with_capacity(MAP_SIZE);
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for _ in 0..MAP_SIZE {
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n.push(EMPTY_SPACE);
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}
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m.push(n);
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}
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let lines: Vec<String> = BufReader::new(File::open(filename).unwrap())
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.lines()
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.map(|line| line.unwrap())
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.collect();
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let mut min_y = MapSize;
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let mut max_y = 0;
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let mut m: Map = [[' '; MapSize]; MapSize];
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m[500][0] = '+';
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m[500][0] = FOUNTAIN;
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for line in lines.iter() {
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let (x_range, y_range) = find_range_in_line(line.as_str());
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for x in x_range {
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for y in y_range.clone() {
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if y < min_y {
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min_y = y;
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}
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if y > max_y {
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max_y = y;
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}
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m[x][y] = '#';
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}
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}
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}
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m
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(m, MapBounds { min_y, max_y })
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}
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fn pour_over(m: &mut Map, start_x: usize, start_y: usize) {
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let mut frontier: VecDeque<Coord> = VecDeque::new();
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frontier.push_back(Coord { x: start_x, y: start_y });
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while let Some(coord) = frontier.pop_front() {
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match m[coord.x][coord.y] {
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FOUNTAIN => frontier.push_back(Coord { x: coord.x, y: coord.y + 1 }),
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EMPTY_SPACE => {
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m[coord.x][coord.y] = FALLING_WATER;
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if coord.y + 1 < MAP_SIZE {
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match m[coord.x][coord.y + 1] {
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WALL_SPACE => frontier.push_back(Coord { x: coord.x, y: coord.y }),
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EMPTY_SPACE => frontier.push_back(Coord { x: coord.x, y: coord.y + 1 }),
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FALLING_WATER => frontier.push_back(Coord { x: coord.x, y: coord.y }),
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WATER => {
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if m[coord.x + 1][coord.y] == WALL_SPACE || m[coord.x - 1][coord.y] == WALL_SPACE {
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frontier.push_back(Coord { x: coord.x, y: coord.y });
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} else if m[coord.x + 2][coord.y] == WALL_SPACE || m[coord.x - 2][coord.y] == WALL_SPACE {
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frontier.push_back(Coord { x: coord.x, y: coord.y });
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} else if m[coord.x + 1][coord.y] == FALLING_WATER || m[coord.x - 1][coord.y] == FALLING_WATER {
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frontier.push_back(Coord { x: coord.x, y: coord.y });
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}
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},
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_ => {},
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}
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}
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},
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WALL_SPACE => {},
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FALLING_WATER => {
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let mut found_down = false;
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// go left as far as possible
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for x in (0..coord.x).rev() {
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match m[x][coord.y] {
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EMPTY_SPACE => {
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if m[x][coord.y + 1] == EMPTY_SPACE {
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found_down = true;
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let c = Coord { x: x, y: coord.y };
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if !frontier.contains(&c) {
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frontier.push_back(c);
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}
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break;
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} else {
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m[x][coord.y] = WATER;
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}
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},
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WATER => {},
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FALLING_WATER => {},
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_ => break,
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}
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}
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// go right as far as possible
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for x in (coord.x + 1)..MAP_SIZE {
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match m[x][coord.y] {
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EMPTY_SPACE => {
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if m[x][coord.y + 1] == EMPTY_SPACE {
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found_down = true;
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let c = Coord { x: x, y: coord.y };
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if !frontier.contains(&c) {
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frontier.push_back(c);
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}
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break;
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} else {
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m[x][coord.y] = WATER;
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}
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},
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WATER => {},
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FALLING_WATER => {},
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_ => break,
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}
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}
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// if no down, then push the square up
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if !found_down {
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let c = Coord { x: coord.x, y: coord.y - 1 };
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if !frontier.contains(&c) {
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frontier.push_back(c);
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}
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}
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},
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WATER => {},
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_ => panic!("invalid map square at {:#?}", coord),
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}
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}
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}
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fn count_water(m: &Map, bounds: &MapBounds) -> usize {
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let mut squares: usize = 0;
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for y in bounds.min_y..=bounds.max_y {
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for x in 0..MAP_SIZE {
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if m[x][y] == WATER || m[x][y] == FALLING_WATER {
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squares += 1;
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}
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}
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}
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squares
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}
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fn count_resting_water(m: &Map, bounds: &MapBounds) -> usize {
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let mut squares: usize = 0;
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for y in bounds.min_y..=bounds.max_y {
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for x in 0..MAP_SIZE {
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if m[x][y] == WATER {
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squares += 1;
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}
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if m[x][y] == FALLING_WATER {
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if m[x - 1][y] == WATER || m[x + 1][y] == WATER {
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squares += 1;
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}
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}
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}
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}
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squares
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}
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fn main() {
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let (mut m, bounds) = build_map_from_file("input");
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pour_over(&mut m, 500, 0);
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print_map(&m, 0, MAP_SIZE - 1, 0, MAP_SIZE - 1);
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let water_squares = count_water(&m, &bounds);
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println!("found {} water squares", water_squares);
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let resting_squares = count_resting_water(&m, &bounds);
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println!("found {} resting water squares", resting_squares);
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}
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#[cfg(test)]
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@ -52,4 +215,22 @@ mod tests {
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assert_eq!(x_range, (100..101));
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assert_eq!(y_range, (100..103));
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}
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#[test]
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fn test_backwards_range_from_line() {
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let line = "y=99, x=1..5";
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let (x_range, y_range) = find_range_in_line(line);
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assert_eq!(x_range, (1..6));
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assert_eq!(y_range, (99..100));
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}
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#[test]
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fn test_sample_data() {
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let (mut m, bounds) = build_map_from_file("test-input");
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pour_over(&mut m, 500, 0);
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let water_squares = count_water(&m, &bounds);
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assert_eq!(water_squares, 57);
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let resting_squares = count_resting_water(&m, &bounds);
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assert_eq!(resting_squares, 29);
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}
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}
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