Day 12 part 2

This commit is contained in:
Daniel Flanagan 2022-12-15 03:18:42 -06:00
parent 4cb8102d64
commit 3bd3646290
Signed by: lytedev
GPG key ID: 5B2020A0F9921EF4

View file

@ -3,11 +3,100 @@ use std::collections::HashSet;
mod common;
type Input = (Vec<Vec<u8>>, (usize, usize), (usize, usize));
struct Input {
map: Vec<Vec<u8>>,
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<usize>> = vec![];
let mut previous_bests: Vec<Vec<Option<(usize, usize)>>> = 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<usize>> = vec![];
let mut previous_bests: Vec<Vec<Option<(usize, usize)>>> = 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));
}
}