Add solution for 2022 day 09 part 2
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@ -12,7 +12,7 @@
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| 06 | ✓ | ✓ | [Rust] |
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| 07 | ✓ | ✓ | [Rust] |
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| 08 | ✓ | ✓ | [Rust] |
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| 09 | ✓ | | [Rust] |
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| 09 | ✓ | ✓ | [Rust] |
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8
2022/day-09/inputs/test2.txt
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8
2022/day-09/inputs/test2.txt
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@ -0,0 +1,8 @@
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R 5
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U 8
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L 8
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D 3
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R 17
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D 10
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L 25
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U 20
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@ -1,6 +1,6 @@
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use std::{env, io};
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use aoc_2022_09::{parse_input, Instruction, Position, VisitedMap};
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use aoc_2022_09::{parse_input, Rope, Visited};
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fn main() -> io::Result<()> {
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let infile_path = env::args().nth(1).expect("input file");
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@ -14,69 +14,18 @@ fn main() -> io::Result<()> {
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fn solve(path: &str) -> io::Result<usize> {
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let instructions = parse_input(path)?;
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let mut rope = Rope::new(2);
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let mut tail_visited = Visited::new();
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let mut head_pos = Position(0, 0);
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let mut tail_pos = Position(0, 0);
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let mut tail_visited = VisitedMap::new();
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tail_visited.insert(tail_pos.clone(), 1);
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tail_visited.insert(rope.tail().unwrap().clone());
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for instruction in instructions {
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(head_pos, tail_pos) =
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apply_instruction(&instruction, &head_pos, &tail_pos, &mut tail_visited);
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instruction.apply_to_rope(&mut rope, &mut tail_visited);
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}
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Ok(tail_visited.len())
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}
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fn apply_instruction(
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instruction: &Instruction,
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head_pos: &Position,
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tail_pos: &Position,
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tail_visited: &mut VisitedMap,
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) -> (Position, Position) {
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let mut tmp_head_pos = head_pos.clone();
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let mut tmp_tail_pos = tail_pos.clone();
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let (change, amount) = match *instruction {
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Instruction::Up(dist) => (Position(1, 0), dist),
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Instruction::Right(dist) => (Position(0, 1), dist),
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Instruction::Left(dist) => (Position(0, -1), dist),
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Instruction::Down(dist) => (Position(-1, 0), dist),
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};
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for _ in 1..=amount {
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tmp_head_pos += change.clone();
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let dx = tmp_head_pos.0 - tmp_tail_pos.0;
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let dxa = dx.abs();
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let dy = tmp_head_pos.1 - tmp_tail_pos.1;
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let dya = dy.abs();
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let same_row = tmp_head_pos.0 == tmp_tail_pos.0;
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let same_col = tmp_head_pos.1 == tmp_tail_pos.1;
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let mut head_changed = false;
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if (!same_row && !same_col) && (dxa > 1 || dya > 1) {
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let x = if dx.is_negative() { -1 } else { 1 };
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let y = if dy.is_negative() { -1 } else { 1 };
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tmp_tail_pos += Position(x, y);
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head_changed = true;
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} else if dxa > 1 || dya > 1 {
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tmp_tail_pos += change.clone();
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head_changed = true;
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}
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if head_changed {
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tail_visited
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.entry(tmp_tail_pos.clone())
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.and_modify(|v| *v += 1)
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.or_insert(1);
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}
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}
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(tmp_head_pos, tmp_tail_pos)
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}
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#[cfg(test)]
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mod test {
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use super::*;
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47
2022/day-09/src/bin/part_two.rs
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47
2022/day-09/src/bin/part_two.rs
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@ -0,0 +1,47 @@
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use std::{env, io};
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use aoc_2022_09::{parse_input, Rope, Visited};
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fn main() -> io::Result<()> {
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let infile_path = env::args().nth(1).expect("input file");
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let result = solve(&infile_path)?;
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println!("{result}");
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Ok(())
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}
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fn solve(path: &str) -> io::Result<usize> {
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let instructions = parse_input(path)?;
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let mut rope = Rope::new(10);
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let mut tail_visited = Visited::new();
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tail_visited.insert(rope.tail().unwrap().clone());
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for instruction in instructions {
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instruction.apply_to_rope(&mut rope, &mut tail_visited);
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}
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Ok(tail_visited.len())
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn sample() {
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let result = solve("inputs/test.txt").unwrap();
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assert_eq!(1, result);
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let result = solve("inputs/test2.txt").unwrap();
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assert_eq!(36, result);
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}
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#[test]
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fn puzzle() {
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let result = solve("inputs/puzzle.txt").unwrap();
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assert_eq!(2273, result);
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}
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}
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@ -1,32 +1,80 @@
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use std::{
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collections::HashMap,
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collections::HashSet,
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fs::File,
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io::{self, BufRead, BufReader},
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ops::{Add, AddAssign},
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path::Path,
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str::FromStr,
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};
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#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
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pub struct Position(pub isize, pub isize);
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pub type Visited = HashSet<Knot>;
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impl Add for Position {
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type Output = Self;
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#[derive(Debug)]
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pub struct Rope(Vec<Knot>);
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fn add(self, rhs: Self) -> Self::Output {
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Self(self.0 + rhs.0, self.1 + rhs.0)
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impl Rope {
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pub fn new(len: usize) -> Self {
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Self(vec![Knot::default(); len])
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}
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pub fn move_head(&mut self, change: (isize, isize)) {
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let mut knots = self.0.iter_mut();
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let mut next_a = knots.next();
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next_a.as_mut().map(|head_knot| {
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head_knot.0 += change.0;
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head_knot.1 += change.1;
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});
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let mut next_b = knots.next();
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loop {
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if next_a.is_some() && next_b.is_some() {
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next_a.as_mut().map(|knot_a| {
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next_b.as_mut().map(|knot_b| {
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knot_b.follow(&knot_a);
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});
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});
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next_a = next_b;
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next_b = knots.next();
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} else {
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break;
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}
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}
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}
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pub fn tail(&self) -> Option<&Knot> {
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self.0.last()
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}
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}
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impl AddAssign for Position {
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fn add_assign(&mut self, rhs: Self) {
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self.0 += rhs.0;
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self.1 += rhs.1;
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#[derive(Debug, Default, Clone, PartialEq, Eq, Hash)]
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pub struct Knot(isize, isize);
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impl Knot {
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pub fn follow(&mut self, other: &Self) {
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let dx = other.0 - self.0;
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let dxa = dx.abs();
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let dy = other.1 - self.1;
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let dya = dy.abs();
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let same_row = self.0 == other.0;
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let same_col = self.1 == other.1;
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let x = if dx.is_negative() { -1 } else { 1 };
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let y = if dy.is_negative() { -1 } else { 1 };
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if (!same_row && !same_col) && (dxa > 1 || dya > 1) {
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self.0 += x;
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self.1 += y;
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} else if dxa > 1 {
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self.0 += x;
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} else if dya > 1 {
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self.1 += y;
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}
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}
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}
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pub type VisitedMap = HashMap<Position, u32>;
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#[derive(Debug)]
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pub enum Instruction {
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Up(isize),
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@ -59,6 +107,29 @@ impl FromStr for Instruction {
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}
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}
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impl Instruction {
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pub fn apply_to_rope(&self, rope: &mut Rope, tail_visited: &mut Visited) {
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let (change, amount) = match *self {
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Instruction::Up(dist) => ((1, 0), dist),
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Instruction::Right(dist) => ((0, 1), dist),
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Instruction::Left(dist) => ((0, -1), dist),
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Instruction::Down(dist) => ((-1, 0), dist),
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};
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for _ in 0..amount {
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let old_tail = rope.tail().unwrap().clone();
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rope.move_head(change);
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let new_tail = rope.tail().unwrap();
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if old_tail != *new_tail {
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tail_visited.insert(new_tail.clone());
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}
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}
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}
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}
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pub fn parse_input<P>(path: P) -> io::Result<Vec<Instruction>>
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where
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P: AsRef<Path>,
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