185 lines
5.6 KiB
Rust
185 lines
5.6 KiB
Rust
use grid::*;
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use intcode::*;
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use itertools::Itertools;
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use std::char;
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use std::collections::{HashMap, HashSet};
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use std::fmt;
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#[derive(Debug, PartialEq, Eq, Hash, Clone)]
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struct Movement {
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rotation: i8,
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distance: u8,
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}
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impl fmt::Display for Movement {
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fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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let dir_char = if self.rotation == 1 { 'R' } else { 'L' };
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write!(f, "{},{}", dir_char, self.distance)
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}
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}
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/// The main reason I use a hashmap here (instead of a 2D vector)
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/// is that my abstractions for ascii stuff all use maps ヽ( ゚ヮ・)ノ
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fn build_field(input: &[i64]) -> HashMap<Position2D, char> {
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IntComputer::without_params(input.to_vec())
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.get_all_outputs()
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.iter()
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.map(|n| char::from_u32(*n as u32).unwrap())
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.collect::<String>()
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.lines()
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.rev()
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.enumerate()
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.flat_map(move |(y, s)| s.chars().enumerate().map(move |(x, c)| ((x, y).into(), c)))
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.collect()
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}
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fn part1(field: &HashMap<Position2D, char>) -> i64 {
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// For some reason, the math for part 1 is upside down. This compensates for that. ¯\_(ツ)_/¯
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let max_y = field.keys().max_by_key(|p| p.y).unwrap().y;
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field
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.iter()
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.filter(|(pos, obj)| {
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*obj == &'#'
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&& pos
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.neighbors()
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.iter()
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.all(|(_, p)| field.get(&p) == Some(&'#'))
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})
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.fold(0, |acc, (pos, _)| acc + pos.x * (max_y - pos.y))
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}
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fn part2(field: &HashMap<Position2D, char>) -> Vec<i64> {
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let movements = find_all_movements(&field);
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let mut functions: Vec<_> = split_into_functions(&movements)
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.into_iter()
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// To remove duplicates
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.collect::<HashSet<_>>()
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.into_iter()
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.zip(['A', 'B', 'C'].iter())
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.collect();
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// Get them in order A, B, C. Makes the output easier later.
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functions.sort_by_key(|(_, c)| c.to_owned());
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let function_calls = get_function_calls(&movements, &functions);
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(function_calls.iter().join(",")
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+ "\n"
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+ &functions
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.into_iter()
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.map(|(f, _)| function_to_string(f))
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.join("\n")
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+ "\nn\n")
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.chars()
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.map(|c| c as i64)
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.rev()
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.collect()
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}
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#[rustfmt::skip]
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fn find_all_movements(field: &HashMap<Position2D, char>) -> Vec<Movement> {
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let mut robot_position = field.iter().find(|(_, c)| *c == &'^').unwrap().0.to_owned();
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let mut robot_direction = Direction::Up;
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let mut commands = Vec::new();
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loop {
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let mut steps = 0;
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// Check if the next valid tile is to the left or the right
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let turn = ((field.get(&(robot_position + (robot_direction + 1))) == Some(&'#')) as i8) * 2 - 1;
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robot_direction += turn;
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while field.get(&(robot_position + robot_direction)) == Some(&'#') {
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robot_position += robot_direction;
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steps += 1;
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}
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commands.push(Movement {
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distance: steps,
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rotation: turn,
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});
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// hit the dead end -> end of scaffolding
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if robot_position.neighbors().iter().filter(|(_, p)| field.get(p) == Some(&'#')).count() == 1 {
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break;
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}
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}
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commands
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}
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fn function_to_string(function: &[Movement]) -> String {
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function.iter().map(|m| m.to_string()).join(",")
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}
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fn find_reoccuring_segments<'a>(
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commands: &'a [Movement],
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previous_segments: &[&'a [Movement]],
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starting_pos: &mut usize,
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length: usize,
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) -> Option<(usize, usize, &'a [Movement])> {
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let reference = commands[*starting_pos..].windows(length).next().unwrap();
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// If the segment we’re currently looking at (reference) is already in our function list,
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// add it with the highest priority. (We’ll deduplicate later)
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if previous_segments.contains(&reference) {
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return Some((length, 99, reference));
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}
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let dupes = commands[*starting_pos..]
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.windows(length)
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.filter(|&w| w == reference)
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.count();
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if dupes > 1 {
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Some((length, dupes, reference))
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} else {
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None
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}
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}
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/**
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* From each position, try to find the slice of the next 2-4 (inclusive)
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* elements that reoccur as often as possible in the output.
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*/
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fn split_into_functions<'a>(commands: &'a [Movement]) -> Vec<&'a [Movement]> {
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let mut pos = 0;
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let mut segments = Vec::new();
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while pos < commands.len() - 4 {
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if let Some((segment_length, _, mov)) = (2..=4)
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.filter_map(|i| find_reoccuring_segments(commands, &segments, &mut pos, i))
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// Segments are rated by length and number of occurences
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.max_by_key(|(x, y, _)| x * y)
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{
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pos += segment_length;
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segments.push(mov);
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}
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}
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segments
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}
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#[rustfmt::skip]
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/// Find matching function calls for all movement sequences.
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fn get_function_calls<'a>(
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movements: &'a[Movement],
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functions: &[(&'a [Movement], &'a char)],
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) -> Vec<char> {
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let mut function_calls = Vec::new();
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let mut pos = 0;
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while pos < movements.len() {
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for i in 1.. {
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if let Some((_, chr)) = functions.iter().find(|(m, _)| m == &&movements[pos..pos + i]) {
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function_calls.push(chr.to_owned().to_owned());
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pos += i;
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break;
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}
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}
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}
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function_calls
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}
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fn main() {
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let mut input = read_input();
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let field = build_field(&input);
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let p1 = part1(&field);
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println!("Part 1: {}", p1);
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input[0] = 2;
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let program = part2(&field);
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println!(
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"Part 2: {:?}",
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IntComputer::new(input, 0, program)
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.get_all_outputs()
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.pop()
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.unwrap()
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);
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}
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