1use crate::util::grid::*;
22use crate::util::parse::*;
23use crate::util::slice::*;
24use std::collections::VecDeque;
25
26type Input = (u32, u32);
27
28pub fn parse(input: &str) -> Input {
29 let grid = Grid::parse(input);
30 let found: Vec<_> =
31 grid.bytes.iter().enumerate().filter(|(_, b)| b.is_ascii_digit()).map(|(i, _)| i).collect();
32
33 let width = grid.width as usize;
34 let stride = found.len();
35 let mut distance = vec![0; stride * stride];
36
37 let mut todo = VecDeque::new();
39 let mut visited = vec![0; grid.bytes.len()];
40
41 for start in found {
42 let from = grid.bytes[start].to_decimal() as usize;
43
44 todo.push_back((start, 0));
45 visited[start] = start;
46
47 while let Some((index, steps)) = todo.pop_front() {
48 if grid.bytes[index].is_ascii_digit() {
49 let to = grid.bytes[index].to_decimal() as usize;
50 distance[stride * from + to] = steps;
51 }
52
53 for next in [index + 1, index - 1, index + width, index - width] {
54 if grid.bytes[next] != b'#' && visited[next] != start {
55 visited[next] = start;
56 todo.push_back((next, steps + 1));
57 }
58 }
59 }
60 }
61
62 let mut part_one = u32::MAX;
64 let mut part_two = u32::MAX;
65 let mut indices: Vec<_> = (1..stride).collect();
66
67 indices.permutations(|slice| {
68 let link = |from, to| distance[stride * from + to];
69
70 let first = link(0, slice[0]);
71 let middle = slice.windows(2).map(|w| link(w[0], w[1])).sum::<u32>();
72 let last = link(slice[slice.len() - 1], 0);
73
74 part_one = part_one.min(first + middle);
75 part_two = part_two.min(first + middle + last);
76 });
77
78 (part_one, part_two)
79}
80
81pub fn part1(input: &Input) -> u32 {
82 input.0
83}
84
85pub fn part2(input: &Input) -> u32 {
86 input.1
87}