aoc2023/day6: Add solution

Signed-off-by: Andrej Orsula <orsula.andrej@gmail.com>

README.md

@@ -24,6 +24,7 @@ My solutions to [Advent of Code](https://adventofcode.com) puzzles.
 |   3   | [Gear Ratios](https://adventofcode.com/2023/day/3)            | [`day3.rs`](aoc2023/src/day3.rs) |
 |   4   | [Scratchcards](https://adventofcode.com/2023/day/4)           | [`day4.rs`](aoc2023/src/day4.rs) |
 |   5   | [If You Give A Seed ...](https://adventofcode.com/2023/day/5) | [`day5.rs`](aoc2023/src/day5.rs) |
+|   6   | [Wait For It](https://adventofcode.com/2023/day/6)            | [`day6.rs`](aoc2023/src/day6.rs) |
 
 </td><td>
 
@@ -34,6 +35,7 @@ My solutions to [Advent of Code](https://adventofcode.com) puzzles.
 | 1.146 µs  | 429.6 µs |
 | 58.79 µs  | 27.72 µs |
 | 19.61 µs  | 5.510 µs |
+| 1.432 µs  | 0.345 µs |
 
 </td><td>
 
@@ -44,6 +46,7 @@ My solutions to [Advent of Code](https://adventofcode.com) puzzles.
 | 0.419 µs  | 308.1 µs |
 | 53.39 µs  | 28.44 µs |
 | 16.38 µs  | 19.364 s |
+| 0.513 µs  | 2.463 ms |
 
 </td></tr>
 </table>

aoc2023/input/2023/day6.txt

@@ -0,0 +1,2 @@
+Time:        57     72     69     92
+Distance:   291   1172   1176   2026

aoc2023/src/day6.rs

@@ -0,0 +1,78 @@
+use aoc_runner_derive::{aoc, aoc_generator};
+
+#[aoc_generator(day6)]
+fn parse(input: &str) -> smallvec::SmallVec<[utils::RaceData; 4]> {
+    use itertools::Itertools;
+
+    let (times, distances) = input
+        .lines()
+        .map(|line| line.split(':').last().unwrap().split_ascii_whitespace())
+        .collect_tuple()
+        .unwrap();
+    times
+        .into_iter()
+        .zip(distances)
+        .map(|(time, distance)| utils::RaceData {
+            time: time.to_owned(),
+            distance: distance.to_owned(),
+        })
+        .collect()
+}
+
+mod utils {
+    pub struct RaceData {
+        pub time: String,
+        pub distance: String,
+    }
+
+    impl RaceData {
+        pub fn n_record_breaks(&self) -> u64 {
+            let (time, distance) = (self.time.parse().unwrap(), self.distance.parse().unwrap());
+            match (1..time).find(|j| j * (time - j) > distance) {
+                Some(first_record) => 1 + time - (2 * first_record),
+                _ => 1,
+            }
+        }
+
+        pub fn merge(sequence: &[Self]) -> Self {
+            let (time, distance) = sequence.iter().fold(
+                Default::default(),
+                |(time, distance): (String, String), data| {
+                    (time + &data.time, distance + &data.distance)
+                },
+            );
+            Self { time, distance }
+        }
+    }
+}
+
+#[aoc(day6, part1)]
+fn part1(input: &[utils::RaceData]) -> u64 {
+    input.iter().map(utils::RaceData::n_record_breaks).product()
+}
+
+#[aoc(day6, part2)]
+fn part2(input: &[utils::RaceData]) -> u64 {
+    utils::RaceData::merge(input).n_record_breaks()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    const SAMPLE: &str = indoc! {"
+        Time:      7  15   30
+        Distance:  9  40  200
+    "};
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(SAMPLE)), 288);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(SAMPLE)), 71503);
+    }
+}

aoc2023/src/lib.rs

@@ -3,5 +3,6 @@ pub mod day2;
 pub mod day3;
 pub mod day4;
 pub mod day5;
+pub mod day6;
 
 aoc_runner_derive::aoc_lib! { year = 2023 }