458 lines
12 KiB
Rust
458 lines
12 KiB
Rust
use std::collections::HashSet;
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const INPUT: &str = include_str!("../data/day3.txt");
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pub fn day3a() -> String {
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format!("{}", sum_parts(INPUT.to_owned()))
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}
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pub fn day3b() -> String {
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format!(
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"{}",
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find_gears(INPUT.to_owned())
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.into_iter()
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.map(|gear| gear.ratio())
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.fold(0, |acc, val| acc + val)
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)
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}
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#[derive(Clone, Debug, PartialEq, Eq, Hash)]
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struct Addr {
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row: usize,
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col: usize,
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}
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impl Addr {
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fn halo(&self) -> impl Iterator<Item = Addr> {
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let row = self.row as i32;
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let col = self.col as i32;
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vec![
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(row - 1, col - 1),
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(row, col - 1),
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(row + 1, col - 1),
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//
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(row - 1, col),
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(row, col),
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(row + 1, col),
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//
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(row - 1, col + 1),
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(row, col + 1),
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(row + 1, col + 1),
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]
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.into_iter()
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.filter(|(row, col)| *row >= 0 && *col >= 0)
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.map(|(row, col)| Addr {
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row: row as usize,
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col: col as usize,
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})
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}
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}
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#[derive(Clone, Debug, PartialEq)]
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struct Part {
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value: u32,
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row: usize,
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start: usize,
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end: usize,
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}
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impl Part {
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fn span<'a>(&'a self) -> impl Iterator<Item = Addr> + 'a {
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(self.start..self.end + 1).map(|addr| Addr {
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row: self.row,
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col: addr,
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})
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}
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fn halo<'a>(&'a self, max_row: usize, max_col: usize) -> impl IntoIterator<Item = Addr> {
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println!("{:?}", self);
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let addresses = self
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.span()
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.map(|addr| addr.halo())
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.flatten()
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.filter(|Addr { row, col }| {
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*row as i32 >= 0
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&& *row as i32 <= max_row as i32
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&& *col as i32 >= 0
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&& *col as i32 <= max_col as i32
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})
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.fold(HashSet::new(), |mut acc, val| {
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let _ = acc.insert(val);
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acc
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});
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println!("{:?}", addresses);
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println!("{:?}", self.span().collect::<HashSet<Addr>>());
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println!("{:?}", addresses.difference(&self.span().collect()));
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addresses
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.difference(&self.span().collect())
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.map(|addr| addr.clone())
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.collect::<HashSet<Addr>>()
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}
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}
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#[derive(Clone, Debug, PartialEq)]
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struct Gear(u32, u32);
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impl Gear {
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fn ratio(&self) -> u32 {
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self.0 * self.1
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}
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}
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fn sum_parts(schematic: String) -> u32 {
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parts(schematic)
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.into_iter()
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.fold(0, |acc, val| acc + val.value)
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}
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fn parts(schematic: String) -> Vec<Part> {
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let sc = schematic
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.lines()
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.map(|l| l.to_owned())
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.collect::<Vec<String>>();
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let parts = find_numbers(schematic.clone());
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parts
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.into_iter()
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.filter(|part| is_part(&sc, part.clone()))
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.collect::<Vec<Part>>()
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}
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fn find_gears(schematic: String) -> Vec<Gear> {
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let sc = schematic
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.lines()
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.map(|l| l.to_owned())
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.collect::<Vec<String>>();
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let max_row = sc.len();
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let max_col = sc[0].len();
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let parts = parts(schematic);
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let splats = find_splats(sc)
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.into_iter()
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.map(|addr| {
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Part {
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value: 0,
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row: addr.row,
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start: addr.col,
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end: addr.col,
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}
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.halo(max_row - 1, max_col - 1)
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.into_iter()
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.collect::<HashSet<Addr>>()
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})
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.collect::<Vec<HashSet<Addr>>>();
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let mut gears = vec![];
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for splat in splats {
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let overlap = parts
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.iter()
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.filter(|part| part_within_halo(splat.clone(), (*part).clone()))
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.map(|part| part.clone())
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.collect::<Vec<Part>>();
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if overlap.len() == 2 {
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gears.push(Gear(overlap[0].value, overlap[1].value));
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}
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}
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gears
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}
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fn part_within_halo(halo1: impl IntoIterator<Item = Addr>, part: Part) -> bool {
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let halo1: HashSet<Addr> = halo1.into_iter().collect::<HashSet<Addr>>();
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let halo2: HashSet<Addr> = part.span().into_iter().collect::<HashSet<Addr>>();
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halo1.intersection(&halo2).count() > 0
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}
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fn is_part(schematic: &Vec<String>, part: Part) -> bool {
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part.halo(schematic.len() - 1, schematic[0].len() - 1)
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.into_iter()
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.any(|addr| {
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let cell = schematic[addr.row].chars().nth(addr.col).unwrap();
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!cell.is_digit(10) && cell != '.'
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})
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}
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fn find_numbers(schematic: String) -> Vec<Part> {
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let mut result = vec![];
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for (idx, line) in schematic.lines().enumerate() {
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let mut numbers = find_numbers_in_line(line)
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.into_iter()
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.map(|(value, start, len)| Part {
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value: value,
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row: idx,
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start,
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end: start + len - 1,
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})
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.collect::<Vec<Part>>();
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result.append(&mut numbers);
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}
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result
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}
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fn find_numbers_in_line(line: &str) -> Vec<(u32, usize, usize)> {
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let mut numbers = vec![];
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let mut start_idx: usize = 0;
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let mut number: Option<String> = None;
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for idx in 0..line.len() {
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match (number.take(), line.chars().nth(idx).unwrap()) {
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(None, c) if c.is_digit(10) => {
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start_idx = idx;
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number = Some(String::from(c));
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}
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(Some(mut num), c) if c.is_digit(10) => {
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num.push(c);
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number = Some(num);
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}
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(Some(num), _) => {
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numbers.push((num, start_idx));
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number = None;
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}
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(_, _) => {}
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}
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}
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if let Some(num) = number {
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numbers.push((num, start_idx));
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}
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numbers
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.into_iter()
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.map(|(number, start_idx)| (number.parse::<u32>().unwrap(), start_idx, number.len()))
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.collect()
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}
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fn find_splats(schematic: Vec<String>) -> Vec<Addr> {
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schematic
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.into_iter()
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.enumerate()
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.map(|(row_idx, row)| {
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row.chars()
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.enumerate()
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.filter_map(|(col_idx, c)| {
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if is_splat(c) {
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Some(Addr {
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row: row_idx,
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col: col_idx,
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})
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} else {
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None
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}
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})
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.collect::<Vec<Addr>>()
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})
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.flatten()
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.collect::<Vec<Addr>>()
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}
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fn is_symbol(c: char) -> bool {
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!c.is_digit(10) && c != '.'
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}
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fn is_splat(c: char) -> bool {
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c == '*'
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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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const INPUT: &str = "467..114..
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...*......
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..35..633.
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......#...
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617*......
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.....+.58.
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..592.....
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......755.
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...$.*....
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.664.598..";
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#[test]
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fn part_1() {
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assert_eq!(
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parts(INPUT.to_owned())
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.into_iter()
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.map(|part| part.value)
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.collect::<Vec<u32>>(),
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vec![467, 35, 633, 617, 592, 755, 664, 598]
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);
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assert_eq!(sum_parts(INPUT.to_owned()), 4361);
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}
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#[test]
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fn test_find_numbers() {
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println!("{:?}", find_numbers(INPUT.to_owned()));
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assert_eq!(
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find_numbers(INPUT.to_owned()),
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vec![
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Part {
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value: 467,
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row: 0,
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start: 0,
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end: 2
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},
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Part {
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value: 114,
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row: 0,
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start: 5,
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end: 7
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},
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Part {
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value: 35,
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row: 2,
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start: 2,
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end: 3
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},
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Part {
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value: 633,
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row: 2,
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start: 6,
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end: 8
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},
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Part {
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value: 617,
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row: 4,
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start: 0,
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end: 2
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},
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Part {
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value: 58,
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row: 5,
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start: 7,
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end: 8,
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},
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Part {
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value: 592,
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row: 6,
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start: 2,
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end: 4,
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},
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Part {
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value: 755,
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row: 7,
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start: 6,
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end: 8,
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},
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Part {
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value: 664,
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row: 9,
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start: 1,
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end: 3,
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},
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Part {
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value: 598,
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row: 9,
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start: 5,
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end: 7,
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}
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]
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);
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}
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#[test]
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fn test_find_numbers_in_line() {
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let test_cases = vec![
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("...*......", vec![]),
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(".664.598..", vec![(664, 1, 3), (598, 5, 3)]),
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("..35..633.", vec![(35, 2, 2), (633, 6, 3)]),
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(
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"......883.....*163...782",
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vec![(883, 6, 3), (163, 15, 3), (782, 21, 3)],
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),
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];
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for (input, expected) in test_cases {
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assert_eq!(find_numbers_in_line(input), expected);
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}
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}
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#[test]
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fn test_halo() {
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let schematic = INPUT.lines().map(|l| l.to_owned()).collect::<Vec<String>>();
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let part = Part {
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value: 0,
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row: 0,
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start: 0,
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end: 2,
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};
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assert_eq!(
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part.halo(schematic.len() - 1, schematic[0].len() - 1)
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.into_iter()
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.collect::<HashSet<Addr>>(),
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vec![
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Addr { row: 1, col: 0 },
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Addr { row: 1, col: 1 },
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Addr { row: 1, col: 2 },
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Addr { row: 0, col: 3 },
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Addr { row: 1, col: 3 }
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]
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.into_iter()
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.collect::<HashSet<Addr>>()
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);
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assert_eq!(
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Part {
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value: 0,
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row: 1,
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start: 1,
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end: 1
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}
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.halo(schematic.len() - 1, schematic[0].len() - 1)
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.into_iter()
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.collect::<HashSet<Addr>>(),
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vec![
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Addr { row: 0, col: 1 },
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Addr { row: 2, col: 1 },
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Addr { row: 0, col: 0 },
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Addr { row: 1, col: 0 },
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Addr { row: 2, col: 0 },
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Addr { row: 0, col: 2 },
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Addr { row: 1, col: 2 },
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Addr { row: 2, col: 2 }
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]
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.into_iter()
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.collect::<HashSet<Addr>>()
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);
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assert_eq!(
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Part {
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value: 0,
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row: 6,
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start: 2,
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end: 4,
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}
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.halo(schematic.len() - 1, schematic[0].len() - 1)
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.into_iter()
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.collect::<HashSet<Addr>>(),
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vec![
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Addr { row: 5, col: 2 },
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Addr { row: 7, col: 2 },
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Addr { row: 5, col: 3 },
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Addr { row: 7, col: 3 },
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Addr { row: 5, col: 4 },
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Addr { row: 7, col: 4 },
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Addr { row: 5, col: 1 },
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Addr { row: 6, col: 1 },
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Addr { row: 7, col: 1 },
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Addr { row: 5, col: 5 },
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Addr { row: 6, col: 5 },
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Addr { row: 7, col: 5 },
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]
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.into_iter()
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.collect::<HashSet<Addr>>()
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);
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}
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#[test]
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fn test_find_gears() {
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let gears = find_gears(INPUT.to_owned());
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assert_eq!(gears, vec![Gear(467, 35), Gear(755, 598)]);
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assert_eq!(
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gears.into_iter().map(|g| g.ratio()).collect::<Vec<u32>>(),
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vec![16345, 451490]
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);
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}
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}
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