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+.................=....836......402.755............=.......*.......*....181.62...*.....%........................596......*............#591... +...............764.....................................488.....880.209........416..................183...156..........917................... diff --git a/2023/src/day1.rs b/2023/src/day1.rs index 1692e56..e03df02 100644 --- a/2023/src/day1.rs +++ b/2023/src/day1.rs @@ -1,5 +1,3 @@ -use std::collections::HashMap; - const INPUT: &str = include_str!("../data/day1.txt"); pub fn day1a() -> String { diff --git a/2023/src/day3.rs b/2023/src/day3.rs new file mode 100644 index 0000000..eeb383d --- /dev/null +++ b/2023/src/day3.rs @@ -0,0 +1,428 @@ +use std::collections::HashSet; + +const INPUT: &str = include_str!("../data/day3.txt"); + +pub fn day3a() -> String { + format!("{}", sum_parts(INPUT.to_owned())) +} + +pub fn day3b() -> String { + format!( + "{}", + find_gears(INPUT.to_owned()) + .into_iter() + .map(|gear| gear.ratio()) + .fold(0, |acc, val| acc + val) + ) +} + +#[derive(Clone, Debug, PartialEq)] +struct Addr { + row: usize, + start: usize, + end: usize, +} + +impl Addr { + fn span(&self) -> Vec<(usize, usize)> { + (self.start..self.end + 1) + .map(|addr| (self.row, addr)) + .collect() + } +} + +#[derive(Clone, Debug, PartialEq)] +struct Gear(u32, u32); + +impl Gear { + fn ratio(&self) -> u32 { + self.0 * self.1 + } +} + +fn sum_parts(schematic: String) -> u32 { + parts(schematic).into_iter().fold(0, |acc, val| acc + val.0) +} + +fn parts(schematic: String) -> Vec<(u32, Addr)> { + let sc = schematic + .lines() + .map(|l| l.to_owned()) + .collect::>(); + let numbers = find_numbers(schematic.clone()); + numbers + .into_iter() + .filter(|number| is_part(&sc, number)) + .collect::>() +} + +fn find_gears(schematic: String) -> Vec { + let sc = schematic + .lines() + .map(|l| l.to_owned()) + .collect::>(); + let max_row = sc.len(); + let max_col = sc[0].len(); + let parts = parts(schematic); + let splats = find_splats(sc) + .into_iter() + .map(|(row, col)| { + halo( + Addr { + row, + start: col, + end: col, + }, + max_row - 1, + max_col - 1, + ) + }) + .collect::>>(); + + let mut gears = vec![]; + for splat in splats { + let overlap = parts + .iter() + .filter(|part| part_within_halo(splat.clone(), part.1.clone())) + .map(|part| part.0) + .collect::>(); + if overlap.len() == 2 { + gears.push(Gear(overlap[0], overlap[1])); + } + } + + gears +} + +fn part_within_halo(halo1: Vec<(usize, usize)>, part: Addr) -> bool { + let halo1: HashSet<(usize, usize)> = halo1.into_iter().collect::>(); + let halo2: HashSet<(usize, usize)> = + part.span().into_iter().collect::>(); + + halo1.intersection(&halo2).count() > 0 +} + +fn is_part(schematic: &Vec, number: &(u32, Addr)) -> bool { + halo( + number.1.clone(), + schematic.len() - 1, + schematic[0].len() - 1, + ) + .into_iter() + .any(|(row, col)| { + let cell = schematic[row].chars().nth(col).unwrap(); + !cell.is_digit(10) && cell != '.' + }) +} + +fn halo(addr: Addr, max_row: usize, max_col: usize) -> Vec<(usize, usize)> { + let mut halo: Vec<(i32, i32)> = vec![]; + + for r in addr.start..addr.end + 1 { + halo.push((addr.row as i32 - 1, r as i32)); + halo.push((addr.row as i32 + 1, r as i32)); + } + + halo.push((addr.row as i32 - 1, addr.start as i32 - 1)); + halo.push((addr.row as i32, addr.start as i32 - 1)); + halo.push((addr.row as i32 + 1, addr.start as i32 - 1)); + halo.push((addr.row as i32 - 1, addr.end as i32 + 1)); + halo.push((addr.row as i32, addr.end as i32 + 1)); + halo.push((addr.row as i32 + 1, addr.end as i32 + 1)); + + halo.into_iter() + .filter(|(row, col)| { + *row >= 0 && *row <= max_row as i32 && *col >= 0 && *col <= max_col as i32 + }) + .map(|(row, col)| (row as usize, col as usize)) + .collect() +} + +fn find_numbers(schematic: String) -> Vec<(u32, Addr)> { + let mut result = vec![]; + for (idx, line) in schematic.lines().enumerate() { + let mut numbers = find_numbers_in_line(line) + .into_iter() + .map(|(number, start, len)| { + ( + number, + Addr { + row: idx, + start, + end: start + len - 1, + }, + ) + }) + .collect::>(); + result.append(&mut numbers); + } + result +} + +fn find_numbers_in_line(line: &str) -> Vec<(u32, usize, usize)> { + let mut numbers = vec![]; + + let mut start_idx: usize = 0; + let mut number: Option = None; + + for idx in 0..line.len() { + match (number.take(), line.chars().nth(idx).unwrap()) { + (None, c) if c.is_digit(10) => { + start_idx = idx; + number = Some(String::from(c)); + } + (Some(mut num), c) if c.is_digit(10) => { + num.push(c); + number = Some(num); + } + (Some(num), _) => { + numbers.push((num, start_idx)); + number = None; + } + (_, _) => {} + } + } + + if let Some(num) = number { + numbers.push((num, start_idx)); + } + + numbers + .into_iter() + .map(|(number, start_idx)| (number.parse::().unwrap(), start_idx, number.len())) + .collect() +} + +fn find_splats(schematic: Vec) -> Vec<(usize, usize)> { + schematic + .into_iter() + .enumerate() + .map(|(row_idx, row)| { + row.chars() + .enumerate() + .filter_map(|(col_idx, c)| { + if is_splat(c) { + Some((row_idx, col_idx)) + } else { + None + } + }) + .collect::>() + }) + .flatten() + .collect::>() +} + +fn is_symbol(c: char) -> bool { + !c.is_digit(10) && c != '.' +} + +fn is_splat(c: char) -> bool { + c == '*' +} + +#[cfg(test)] +mod test { + use super::*; + + const INPUT: &str = "467..114.. +...*...... +..35..633. +......#... +617*...... +.....+.58. +..592..... +......755. +...$.*.... +.664.598.."; + + #[test] + fn part_1() { + assert_eq!( + parts(INPUT.to_owned()) + .into_iter() + .map(|part| part.0) + .collect::>(), + vec![467, 35, 633, 617, 592, 755, 664, 598] + ); + + assert_eq!(sum_parts(INPUT.to_owned()), 4361); + } + + #[test] + fn test_find_numbers() { + println!("{:?}", find_numbers(INPUT.to_owned())); + assert_eq!( + find_numbers(INPUT.to_owned()), + vec![ + ( + 467, + Addr { + row: 0, + start: 0, + end: 2 + } + ), + ( + 114, + Addr { + row: 0, + start: 5, + end: 7 + } + ), + ( + 35, + Addr { + row: 2, + start: 2, + end: 3 + } + ), + ( + 633, + Addr { + row: 2, + start: 6, + end: 8 + } + ), + ( + 617, + Addr { + row: 4, + start: 0, + end: 2 + } + ), + ( + 58, + Addr { + row: 5, + start: 7, + end: 8, + } + ), + ( + 592, + Addr { + row: 6, + start: 2, + end: 4, + } + ), + ( + 755, + Addr { + row: 7, + start: 6, + end: 8, + } + ), + ( + 664, + Addr { + row: 9, + start: 1, + end: 3, + } + ), + ( + 598, + Addr { + row: 9, + start: 5, + end: 7, + } + ) + ] + ); + } + + #[test] + fn test_find_numbers_in_line() { + let test_cases = vec![ + ("...*......", vec![]), + (".664.598..", vec![(664, 1, 3), (598, 5, 3)]), + ("..35..633.", vec![(35, 2, 2), (633, 6, 3)]), + ( + "......883.....*163...782", + vec![(883, 6, 3), (163, 15, 3), (782, 21, 3)], + ), + ]; + for (input, expected) in test_cases { + assert_eq!(find_numbers_in_line(input), expected); + } + } + + #[test] + fn test_halo() { + let schematic = INPUT.lines().map(|l| l.to_owned()).collect::>(); + let number = Addr { + row: 0, + start: 0, + end: 2, + }; + assert_eq!( + halo(number, schematic.len() - 1, schematic[0].len() - 1), + vec![(1, 0), (1, 1), (1, 2), (0, 3), (1, 3)] + ); + + assert_eq!( + halo( + Addr { + row: 1, + start: 1, + end: 1 + }, + schematic.len() - 1, + schematic[0].len() - 1 + ), + vec![ + (0, 1), + (2, 1), + (0, 0), + (1, 0), + (2, 0), + (0, 2), + (1, 2), + (2, 2) + ] + ); + assert_eq!( + halo( + Addr { + row: 6, + start: 2, + end: 4, + }, + schematic.len() - 1, + schematic[0].len() - 1 + ), + vec![ + (5, 2), + (7, 2), + (5, 3), + (7, 3), + (5, 4), + (7, 4), + (5, 1), + (6, 1), + (7, 1), + (5, 5), + (6, 5), + (7, 5), + ] + ); + } + + #[test] + fn test_find_gears() { + let gears = find_gears(INPUT.to_owned()); + assert_eq!(gears, vec![Gear(467, 35), Gear(755, 598)]); + assert_eq!( + gears.into_iter().map(|g| g.ratio()).collect::>(), + vec![16345, 451490] + ); + } +} diff --git a/2023/src/main.rs b/2023/src/main.rs index 0dd1945..4067764 100644 --- a/2023/src/main.rs +++ b/2023/src/main.rs @@ -1,5 +1,6 @@ mod day1; mod day2; +mod day3; fn main() { let day = std::env::args().skip(1).next(); @@ -9,6 +10,8 @@ fn main() { Some("1b") => day1::day1b(), Some("2a") => day2::day2a(), Some("2b") => day2::day2b(), + Some("3a") => day3::day3a(), + Some("3b") => day3::day3b(), _ => panic!("unrecognized day"), };