71 lines
2.1 KiB
Rust
71 lines
2.1 KiB
Rust
#![feature(test, array_windows)]
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extern crate test;
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use aoc2022::{boilerplate, common::*};
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use std::iter::repeat;
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const DAY: usize = 14;
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const X_OFFSET: usize = 300;
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const SAND_SOURCE: (usize, usize) = (500 - X_OFFSET, 0);
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const CAVE_HEIGHT: usize = 200;
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const CAVE_WIDTH: usize = CAVE_HEIGHT * 2;
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type Cave = [[bool; CAVE_HEIGHT]; CAVE_WIDTH];
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type Parsed = (Cave, usize);
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fn parse_input(raw: &str) -> Parsed {
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let mut cave = [[false; CAVE_HEIGHT]; CAVE_WIDTH];
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let mut max_y = 0;
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for line in raw.lines() {
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let segments: Vec<(usize, usize)> =
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line.split(" -> ").map(|s| s.split_once(',').unwrap()).map(|(x, y)| (parse_num::<usize>(x) - X_OFFSET, parse_num(y))).collect();
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for &[(x1, y1), (x2, y2)] in segments.array_windows() {
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max_y = max_y.max(y1).max(y2);
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for (x, y) in ((x1.min(x2))..=(x1.max(x2))).flat_map(|x| repeat(x).zip((y1.min(y2))..=(y1.max(y2)))) {
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cave[x][y] = true;
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}
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}
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}
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(cave, max_y)
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}
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fn simulate((x, y): (usize, usize), cave: &Cave) -> Option<(usize, usize)> {
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if y >= CAVE_HEIGHT - 1 {
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None
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} else if !cave[x][y + 1] {
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simulate((x, y + 1), cave)
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} else if !cave[x - 1][y + 1] {
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simulate((x - 1, y + 1), cave)
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} else if !cave[x + 1][y + 1] {
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simulate((x + 1, y + 1), cave)
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} else {
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Some((x, y))
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}
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}
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fn part1((cave, _): &Parsed) -> usize {
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(0..).scan(cave.to_owned(), |cave, _| simulate(SAND_SOURCE, &cave).map(|(x, y)| cave[x][y] = true)).count()
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}
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fn part2((cave, max_y): &Parsed) -> usize {
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let mut cave = cave.to_owned();
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let mut sand = 0;
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cave.iter_mut().for_each(|row| row[max_y + 2] = true);
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while !cave[SAND_SOURCE.0][SAND_SOURCE.1] {
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let (x, y) = simulate(SAND_SOURCE, &cave).unwrap();
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cave[x][y] = true;
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sand += 1;
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}
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sand
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}
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boilerplate! {
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TEST_INPUT == "498,4 -> 498,6 -> 496,6
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503,4 -> 502,4 -> 502,9 -> 494,9",
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tests: {
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part1: { TEST_INPUT => 24 },
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part2: { TEST_INPUT => 93 },
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},
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bench1 == 674,
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bench2 == 24958,
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bench_parse: |(_, y): &Parsed| *y => 161,
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}
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