99 lines
2.3 KiB
Rust
99 lines
2.3 KiB
Rust
use std::collections::HashSet;
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fn parse(input: &str) -> Vec<(i64, i64)> {
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input
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.lines()
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.map(|s| {
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let (y, x) = s.split_once(',').unwrap();
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(x.parse().unwrap(), y.parse().unwrap())
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})
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.collect()
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}
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fn solve_1(input: &str, steps: usize, range: i64) -> Option<i64> {
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let memory = parse(input);
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let memory: HashSet<_> = memory[..steps].into_iter().collect();
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let mut visited: HashSet<(i64, i64)> = HashSet::new();
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let mut path_length = 0;
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let mut stack: HashSet<_> = [(0, 0)].into_iter().collect();
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let dirs = [(1, 0), (-1, 0), (0, 1), (0, -1)];
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loop {
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path_length += 1;
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let mut new_stack = HashSet::new();
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if stack.is_empty() {
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return None;
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}
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for pos in stack {
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if pos == (range, range) {
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return Some(path_length - 1);
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}
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visited.insert(pos);
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for dir in dirs {
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let new_pos = (pos.0 + dir.0, pos.1 + dir.1);
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if new_pos.0 >= 0 && new_pos.0 <= range && new_pos.1 >= 0 && new_pos.1 <= range {
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if !visited.contains(&new_pos) && !memory.contains(&new_pos) {
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new_stack.insert(new_pos);
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}
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}
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}
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}
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stack = new_stack;
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}
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}
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fn solve_2(input: &str, range: i64) -> (i64, i64) {
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let memory = parse(input);
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for i in 0..memory.len() {
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if solve_1(input, i, range).is_none() {
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return memory[i - 1];
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}
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}
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return (0, 0);
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}
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fn main() {
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println!("Hello, this is Patrick!");
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let input = include_str!("../input.txt");
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let result_1 = solve_1(input, 1024, 70);
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println!(
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"The number of steps of the shortest route from beginning to end is {}",
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result_1.unwrap()
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);
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let result_2 = solve_2(input, 70);
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println!(
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"The first byte that prevents a path being laid is {},{}",
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result_2.1, result_2.0
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);
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_1() {
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let test_input = include_str!("../test.txt");
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assert_eq!(solve_1(test_input, 12, 6).unwrap(), 22);
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}
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#[test]
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fn test_2() {
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let test_input = include_str!("../test.txt");
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assert_eq!(solve_2(test_input, 6), (1, 6));
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}
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}
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