day 6

4 files changed, 97 insertions, 0 deletions

diff --git a/benches/2023.rs b/benches/2023.rs
index a9a610b..ebab90c 100644
--- a/benches/2023.rs
+++ b/benches/2023.rs
@@ -11,6 +11,8 @@ mod day3;
 mod day4;
 #[path = "../src/bin/2023/day5.rs"]
 mod day5;
+#[path = "../src/bin/2023/day6.rs"]
+mod day6;
 // NEXT MOD
 
 day!(2023, 1, day1);
@@ -18,6 +20,7 @@ day!(2023, 2, day2);
 day!(2023, 3, day3);
 day!(2023, 4, day4);
 day!(2023, 5, day5);
+day!(2023, 6, day6);
 // NEXT DAY
 
 fn bench_2023(c: &mut criterion::Criterion) {
@@ -28,6 +31,7 @@ fn bench_2023(c: &mut criterion::Criterion) {
             day_combined!(2023, 3, day3);
             day_combined!(2023, 4, day4);
             day_combined!(2023, 5, day5);
+            day_combined!(2023, 6, day6);
             // NEXT DAY COMBINED
         })
     });
@@ -41,5 +45,6 @@ criterion::criterion_main!(
     bench_2023day3,
     bench_2023day4,
     bench_2023day5,
+    bench_2023day6,
     // NEXT GROUP
 );
diff --git a/data/2023/6.txt b/data/2023/6.txt
new file mode 100644
index 0000000..578cc39
--- /dev/null
+++ b/data/2023/6.txt
@@ -0,0 +1,2 @@
+Time:        40     81     77     72
+Distance:   219   1012   1365   1089
diff --git a/src/bin/2023/day6.rs b/src/bin/2023/day6.rs
new file mode 100644
index 0000000..209cfef
--- /dev/null
+++ b/src/bin/2023/day6.rs
@@ -0,0 +1,88 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+
+use advent_of_code::prelude::*;
+
+#[derive(Debug)]
+pub struct Race {
+    time: i64,
+    distance: i64,
+}
+
+impl Race {
+    fn distance(&self, t: i64) -> i64 {
+        (self.time - t) * t
+    }
+}
+
+pub fn parse(fh: File) -> Result<Vec<Race>> {
+    let mut lines = parse::raw_lines(fh);
+    let time = lines.next().unwrap();
+    let distance = lines.next().unwrap();
+    let times: Vec<_> = time
+        .split(':')
+        .nth(1)
+        .unwrap()
+        .split_whitespace()
+        .map(|s| s.parse().unwrap())
+        .collect();
+    let distances: Vec<_> = distance
+        .split(':')
+        .nth(1)
+        .unwrap()
+        .split_whitespace()
+        .map(|s| s.parse().unwrap())
+        .collect();
+    Ok((0..times.len())
+        .map(|i| Race {
+            time: times[i],
+            distance: distances[i],
+        })
+        .collect())
+}
+
+pub fn part1(races: Vec<Race>) -> Result<i64> {
+    Ok(races
+        .into_iter()
+        .map(|race| -> i64 {
+            (0..race.time)
+                .map(|t| race.distance(t))
+                .filter(|d| *d > race.distance)
+                .count()
+                .try_into()
+                .unwrap()
+        })
+        .product())
+}
+
+pub fn part2(races: Vec<Race>) -> Result<i64> {
+    let mut real_race = Race {
+        time: 0,
+        distance: 0,
+    };
+    for race in races {
+        real_race.time =
+            real_race.time * 10i64.pow(race.time.ilog10() + 1) + race.time;
+        real_race.distance = real_race.distance
+            * 10i64.pow(race.distance.ilog10() + 1)
+            + race.distance;
+    }
+    Ok((0..real_race.time)
+        .map(|t| real_race.distance(t))
+        .filter(|d| *d > real_race.distance)
+        .count()
+        .try_into()
+        .unwrap())
+}
+
+#[test]
+fn test() {
+    assert_eq!(
+        part1(parse(parse::data(2023, 6).unwrap()).unwrap()).unwrap(),
+        861300
+    );
+    assert_eq!(
+        part2(parse(parse::data(2023, 6).unwrap()).unwrap()).unwrap(),
+        28101347
+    );
+}
diff --git a/src/bin/2023/main.rs b/src/bin/2023/main.rs
index 1b896b4..828a8a5 100644
--- a/src/bin/2023/main.rs
+++ b/src/bin/2023/main.rs
@@ -16,6 +16,7 @@ mod day2;
 mod day3;
 mod day4;
 mod day5;
+mod day6;
 // NEXT MOD
 
 #[paw::main]
@@ -27,6 +28,7 @@ fn main(opt: Opt) -> Result<()> {
         3 => advent_of_code::day!(2023, opt.day, opt.puzzle, day3),
         4 => advent_of_code::day!(2023, opt.day, opt.puzzle, day4),
         5 => advent_of_code::day!(2023, opt.day, opt.puzzle, day5),
+        6 => advent_of_code::day!(2023, opt.day, opt.puzzle, day6),
         // NEXT PART
         _ => panic!("unknown day {}", opt.day),
     }