114 lines
3.6 KiB
Rust
114 lines
3.6 KiB
Rust
#![feature(test)]
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extern crate test;
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use std::collections::HashSet;
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use aoc2022::{
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boilerplate,
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common::*,
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grid::{Grid, Position2D, PositionND, VecGrid},
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};
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const DAY: usize = 12;
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type Parsed = (Position2D, Position2D, VecGrid<u8>);
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fn find_and_modify(grid: &mut Vec<Vec<u8>>, needle: u8, replacement: u8) -> (usize, usize) {
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grid.iter_mut()
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.enumerate()
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.find_map(|(x, line)| {
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line.iter_mut()
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.enumerate()
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.find_map(|(y, b)| {
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(b == &needle).then(|| {
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*b = replacement;
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y
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})
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})
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.map(|y| (x, y))
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})
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.unwrap()
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}
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fn parse_input(raw: &str) -> Parsed {
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let mut grid = VecGrid::from_bytes_2d(raw, |b| b);
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let start = find_and_modify(&mut grid.fields, b'S', b'a');
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let start = Position2D::from([start.0, start.1]);
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let end = find_and_modify(&mut grid.fields, b'E', b'z');
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let end = Position2D::from([end.0, end.1]);
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(start, end, grid)
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}
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fn part1((start, end, grid): &Parsed) -> usize {
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let xbounds = 0..grid.len();
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let ybounds = 0..grid.fields[0].len();
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let mut distances = VecGrid { fields: vec![vec![usize::MAX; ybounds.end]; xbounds.end] };
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let mut visited = VecGrid { fields: vec![vec![false; ybounds.end]; xbounds.end] };
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let mut points_to_consider = HashSet::from([*start]);
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distances[*start] = 0;
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let mut curr = *start;
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loop {
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if &curr == end {
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return distances[curr];
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}
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points_to_consider.remove(&curr);
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for n in curr
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.neighbors_no_diagonals()
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.into_iter()
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.filter(|&PositionND([x, y])| xbounds.contains(&(x as usize)) && ybounds.contains(&(y as usize)))
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{
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if !visited[n] {
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if grid[curr] >= grid[n] || grid[n] - grid[curr] == 1 {
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distances[n] = distances[n].min(distances[curr] + 1);
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}
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points_to_consider.insert(n);
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}
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}
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visited[curr] = true;
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curr = *points_to_consider.iter().min_by_key(|&&p| distances[p]).unwrap();
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}
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}
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fn part2((_, end, grid): &Parsed) -> usize {
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let xbounds = 0..grid.len();
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let ybounds = 0..grid.fields[0].len();
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let mut distances = VecGrid { fields: vec![vec![usize::MAX; ybounds.end]; xbounds.end] };
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let mut visited = VecGrid { fields: vec![vec![false; ybounds.end]; xbounds.end] };
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let mut points_to_consider = HashSet::from([*end]);
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distances[*end] = 0;
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let mut curr = *end;
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loop {
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if grid[curr] == b'a' {
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return distances[curr];
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}
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points_to_consider.remove(&curr);
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for n in curr
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.neighbors_no_diagonals()
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.into_iter()
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.filter(|&PositionND([x, y])| xbounds.contains(&(x as usize)) && ybounds.contains(&(y as usize)))
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{
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if !visited[n] {
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if grid[curr] <= grid[n] || grid[curr] - grid[n] == 1 {
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distances[n] = distances[n].min(distances[curr] + 1);
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}
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points_to_consider.insert(n);
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}
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}
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visited[curr] = true;
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curr = *points_to_consider.iter().min_by_key(|&&p| distances[p]).unwrap();
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}
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}
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boilerplate! {
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TEST_INPUT == "Sabqponm
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abcryxxl
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accszExk
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acctuvwj
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abdefghi",
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tests: {
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part1: { TEST_INPUT => 31 },
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part2: { TEST_INPUT => 29 },
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},
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bench1 == 517,
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bench2 == 512,
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bench_parse: |&(PositionND([sx, sy]), PositionND([ex, ey]), _)| ((sx, sy), (ex, ey)) => ((20, 0), (20, 145)),
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}
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