This commit is contained in:
Dory 2024-03-17 16:20:10 -07:00
parent 6a0ed15470
commit 729308742a

View File

@ -2,30 +2,82 @@ use std::env;
use std::fs::File;
use std::io::{self, BufRead};
use std::collections::BinaryHeap;
use std::cmp::Reverse;
use std::cmp::max;
fn find<T: Eq + Copy>(haystack: &Vec<Vec<T>>, needle: T) -> (usize, usize) {
// I just wanna play around with iters; there are better ways...
haystack.iter().enumerate()
.map(|(i, &ref row)|
(i, row.iter().enumerate()
.filter(|(_j, &ref c)| *c == needle)
.map(|(j, _c)| j)
.collect::<Vec<usize>>()))
.filter(|(_i, row)| !row.is_empty())
.map(|(i, row)| (i, *row.iter().nth(0).unwrap()))
.nth(0).unwrap()
fn get(map: &Vec<Vec<i64>>, coord: (usize, usize)) -> i64 {
map[coord.0 as usize][coord.1 as usize]
}
fn main() {
let file = File::open(&env::args().nth(1).unwrap()).unwrap();
let map: Vec<Vec<u8>> = io::BufReader::new(file).lines().flatten()
.map(|line| line.chars().map(|c| c as u8).collect())
.collect();
let (starti, startj) = find(&map, 'S' as u8);
let (endi, endj) = find(&map, 'E' as u8);
let mut map: Vec<Vec<i64>> = Vec::new();
let mut queue = BinaryHeap::new();
let (mut start, mut end) = ((0, 0), (0, 0));
println!("{:?}", map);
println!("{:?}, {:?} -> {:?}, {:?}", starti, startj, endi, endj);
// parse input
for (i, line) in io::BufReader::new(file).lines().flatten().enumerate() {
let mut row: Vec<i64> = Vec::new();
for (j, c) in line.chars().enumerate() {
match c {
'S' => { start = (i, j); row.push('a' as i64); },
'E' => { end = (i, j); row.push('z' as i64); },
c => row.push(c as i64),
}
}
map.push(row);
}
let (height, width) = (map.len(), map[0].len());
let mut costs = vec![vec![i64::MAX; width]; height];
let heur: Vec<Vec<i64>> = (0..height)
.map(|i| (0..width)
.map(|j|
max((i.abs_diff(end.0) + j.abs_diff(end.1)) as i64,
get(&map, end) - get(&map, (i, j))))
.collect())
.collect();
queue.push((-heur[start.0][start.1], start));
costs[start.0][start.1] = 0;
// A*
let answer = loop {
// no route
if queue.is_empty() {
break None;
}
let (_, (i, j)) = queue.pop().unwrap();
let cost = get(&costs, (i, j));
// found destination
if (i, j) == end {
break Some(cost);
}
// handle neighbors
let neighbors = [
(i as i64, (j as i64) - 1),
(i as i64, (j as i64) + 1),
((i as i64) - 1, j as i64),
((i as i64) + 1, j as i64)];
for (nexti, nextj) in neighbors {
if nexti < 0 || nextj < 0
|| nexti >= height as i64 || nextj >= width as i64
|| map[nexti as usize][nextj as usize] > map[i][j] + 1
{
continue;
}
let nexti: usize = nexti as usize;
let nextj: usize = nextj as usize;
let new_cost = cost + 1;
if new_cost < costs[nexti][nextj] {
costs[nexti][nextj] = new_cost;
queue.retain(|(_, (ri, rj))| *ri != nexti || *rj != nextj);
queue.push((-new_cost - heur[nexti][nextj], (nexti, nextj)));
}
}
};
println!("= {:?}", answer);
}