77 lines
2.1 KiB
Rust
77 lines
2.1 KiB
Rust
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use std::{fs, env, collections::HashSet};
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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enum Direction {
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East,
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South,
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Empty
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}
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fn read_input(path: &str) -> String {
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return fs::read_to_string(path).expect("Cannot read file.");
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}
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fn parse_input(s: &str) -> Vec<Vec<Direction>> {
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let mut f: Vec<Vec<Direction>> = vec![];
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for (r, l) in s.lines().enumerate() {
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f.push(vec![]);
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for c in l.chars() {
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f[r].push(match c {
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'>' => { Direction::East }
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'v' => { Direction::South }
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_ => { Direction::Empty }
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});
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}
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}
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return f;
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}
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fn get_next(i: usize, m: usize) -> usize {
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if i == m - 1 { return 0; }
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return i + 1;
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}
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fn apply_step(v: &mut Vec<Vec<Direction>>) -> usize {
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let mut f = HashSet::new();
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let mut o = v.clone();
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for r in 0..v.len() {
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for c in 0..v[r].len() {
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let n = get_next(c, v[r].len());
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if v[r][c] != Direction::East { continue; }
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if v[r][n] != Direction::Empty { continue; }
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if o[r][n] != Direction::Empty { continue; }
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if f.contains(&(r, c)) { continue; }
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f.insert((r, n));
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v[r][n] = Direction::East;
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v[r][c] = Direction::Empty;
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}
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}
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o = v.clone();
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for r in 0..v.len() {
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let n = get_next(r, v.len());
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for c in 0..v[r].len() {
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if v[r][c] != Direction::South { continue; }
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if v[n][c] != Direction::Empty { continue; }
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if o[n][c] != Direction::Empty { continue; }
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if f.contains(&(r, c)) { continue; }
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f.insert((n, c));
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v[n][c] = Direction::South;
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v[r][c] = Direction::Empty;
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}
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}
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return f.len();
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}
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fn main() {
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let args: Vec<String> = env::args().collect();
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for arg in args.iter().skip(1) {
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let input = read_input(&arg);
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let mut vec_in = parse_input(&input);
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let mut i = 1;
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while apply_step(&mut vec_in) != 0 { i += 1; }
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println!("[{}]", &arg);
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println!("\t[Part 1] => Answer is '{}'.", i);
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}
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}
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