From 3bd3646290b798f1f0e9ce68ef2efa0a34510e06 Mon Sep 17 00:00:00 2001 From: Daniel Flanagan Date: Thu, 15 Dec 2022 03:18:42 -0600 Subject: [PATCH] Day 12 part 2 --- 2022/rust/src/day12.rs | 198 ++++++++++++++++++++++------------------- 1 file changed, 107 insertions(+), 91 deletions(-) diff --git a/2022/rust/src/day12.rs b/2022/rust/src/day12.rs index c9355a6..9197843 100644 --- a/2022/rust/src/day12.rs +++ b/2022/rust/src/day12.rs @@ -3,11 +3,100 @@ use std::collections::HashSet; mod common; -type Input = (Vec>, (usize, usize), (usize, usize)); +struct Input { + map: Vec>, + start: (usize, usize), + end: (usize, usize), +} + type Answer = usize; +impl Input { + fn shortest_path_length(&self, s: Option<(usize, usize)>) -> usize { + let s = s.unwrap_or(self.start); + let mut open_set = HashSet::<(usize, usize)>::from([s]); + let mut came_from = HashMap::<(usize, usize), (usize, usize)>::new(); + let mut cheapest_for = HashMap::<(usize, usize), i64>::from([(s, 0)]); + let mut guess_score = HashMap::<(usize, usize), i64>::from([(s, 0)]); + + let h = self.map.len(); + let w = self.map[0].len(); + + // guess_score.get(&(y, x)).unwrap_or(&i64::MAX).clone() + while open_set.len() > 0 { + let (mut y, mut x) = open_set + .iter() + .min_by(|(y1, x1), (y2, x2)| { + guess_score + .get(&(*y1, *x1)) + .unwrap_or(&i64::MAX) + .cmp(&guess_score.get(&(*y2, *x2)).unwrap_or(&i64::MAX)) + }) + .unwrap(); + + if (y, x) == self.end { + let mut n = 0; + while let Some((ny, nx)) = came_from.get(&(y, x)) { + y = *ny; + x = *nx; + n += 1; + } + return n; + } + + open_set.remove(&(y, x)); + let c = self.map[y][x]; + let mut potential_neighbors = vec![]; + if y > 0 { + potential_neighbors.push((y - 1, x)); + } + if y < h - 1 { + potential_neighbors.push((y + 1, x)); + } + if x > 0 { + potential_neighbors.push((y, x - 1)); + } + if x < w - 1 { + potential_neighbors.push((y, x + 1)); + } + for (ny, nx) in potential_neighbors + .iter() + .filter(|(y, x)| (self.map[*y][*x] as i32) - (c as i32) <= 1) + { + let ny = ny.clone(); + let nx = nx.clone(); + let score = guess_score.get(&(y, x)).unwrap_or(&i64::MAX).clone() + 1; + let ns = guess_score.get(&(ny, nx)).unwrap_or(&i64::MAX).clone(); + if score < ns { + came_from.insert((ny, nx), (y, x)); + guess_score.insert((ny, nx), score); + cheapest_for.insert((ny, nx), score + 1); + open_set.insert((ny, nx)); + } + } + } + + let mut distances: Vec> = vec![]; + let mut previous_bests: Vec>> = vec![]; + for y in 0..self.map.len() { + let mut row_distances = vec![]; + let mut row_previous_bests = vec![]; + for _ in 0..self.map[y].len() { + row_distances.push(std::usize::MAX); + row_previous_bests.push(None); + } + distances.push(row_distances); + previous_bests.push(row_previous_bests); + } + distances[s.0][s.1] = 0; + + // no path found + usize::MAX + } +} + fn processed_input(input: &str) -> Input { - let mut result = vec![]; + let mut map = vec![]; let mut start = (0, 0); let mut end = (0, 0); let lines = input @@ -30,110 +119,37 @@ fn processed_input(input: &str) -> Input { c => row.push(c as u8 - 'a' as u8), } } - result.push(row) + map.push(row) } - return (result, start, end); + return Input { map, start, end }; } fn part1(input: &Input) -> Answer { - let mut open_set = HashSet::<(usize, usize)>::from([input.1]); - let mut came_from = HashMap::<(usize, usize), (usize, usize)>::new(); - let mut cheapest_for = HashMap::<(usize, usize), i64>::from([(input.1, 0)]); - let mut guess_score = HashMap::<(usize, usize), i64>::from([(input.1, 0)]); - - let h = input.0.len(); - let w = input.0[0].len(); - - // guess_score.get(&(y, x)).unwrap_or(&i64::MAX).clone() - while open_set.len() > 0 { - let (mut y, mut x) = open_set - .iter() - .min_by(|(y1, x1), (y2, x2)| { - guess_score - .get(&(*y1, *x1)) - .unwrap_or(&i64::MAX) - .cmp(&guess_score.get(&(*y2, *x2)).unwrap_or(&i64::MAX)) - }) - .unwrap(); - - if (y, x) == input.2 { - let mut n = 0; - while let Some((ny, nx)) = came_from.get(&(y, x)) { - y = *ny; - x = *nx; - n += 1; - } - return n; - } - - open_set.remove(&(y, x)); - let c = input.0[y][x]; - let mut potential_neighbors = vec![]; - if y > 0 { - potential_neighbors.push((y - 1, x)); - } - if y < h - 1 { - potential_neighbors.push((y + 1, x)); - } - if x > 0 { - potential_neighbors.push((y, x - 1)); - } - if x < w - 1 { - potential_neighbors.push((y, x + 1)); - } - for (ny, nx) in potential_neighbors - .iter() - .filter(|(y, x)| (input.0[*y][*x] as i32) - (c as i32) <= 1) - { - let ny = ny.clone(); - let nx = nx.clone(); - let score = guess_score.get(&(y, x)).unwrap_or(&i64::MAX).clone() + 1; - let ns = guess_score.get(&(ny, nx)).unwrap_or(&i64::MAX).clone(); - if score < ns { - came_from.insert((ny, nx), (y, x)); - guess_score.insert((ny, nx), score); - cheapest_for.insert((ny, nx), score + 1); - open_set.insert((ny, nx)); - } - } - } - - let mut distances: Vec> = vec![]; - let mut previous_bests: Vec>> = vec![]; - for y in 0..input.0.len() { - let mut row_distances = vec![]; - let mut row_previous_bests = vec![]; - for _ in 0..input.0[y].len() { - row_distances.push(std::usize::MAX); - row_previous_bests.push(None); - } - distances.push(row_distances); - previous_bests.push(row_previous_bests); - } - distances[input.1 .0][input.1 .1] = 0; - - // no path found - usize::MAX + input.shortest_path_length(None) } -fn part2(input: &Input) -> Answer { - let mut possible_starts = HashSet::<(usize, usize)>::from([input.1]); - for y in 0..input.0.len() { - for x in 0..input.0[y].len() { - if input.0[y][x] == 0 { +fn part2(input: Input) -> Answer { + let mut possible_starts = HashSet::<(usize, usize)>::from([input.start]); + for y in 0..input.map.len() { + for x in 0..input.map[y].len() { + if input.map[y][x] == 0 { possible_starts.insert((y, x)); } } } - possible_starts.iter().map(|s| part1((input.0, s, input.2)) - } + + possible_starts + .iter() + .map(|s| input.shortest_path_length(Some(*s))) + .min() + .unwrap() } fn main() { let input_text = common::day_input(12); eprintln!("{}\n\nAbove is your input file.\n\n", input_text); let input = processed_input(&input_text); - common::show_answers(&part1(&input), &part2(&input)) + common::show_answers(&part1(&input), &part2(input)) // common::show_both_answers(&both_parts(&input)) } @@ -155,7 +171,7 @@ abdefghi"; fn test() { let input = processed_input(TEST_INPUT); assert_eq!(part1(&input), 31); - assert_eq!(part2(&input), 0); + assert_eq!(part2(input), 29); // assert_eq!(both_parts(&input), (0, 0)); } }