day 06

Cargo.lock

@@ -77,12 +77,27 @@ dependencies = [
  "rayon",
 ]
 
+[[package]]
+name = "day-06"
+version = "0.0.0"
+dependencies = [
+ "indoc",
+ "nom",
+ "rayon",
+]
+
 [[package]]
 name = "either"
 version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a26ae43d7bcc3b814de94796a5e736d4029efb0ee900c12e2d54c993ad1a1e07"
 
+[[package]]
+name = "indoc"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e186cfbae8084e513daff4240b4797e342f988cecda4fb6c939150f96315fd8"
+
 [[package]]
 name = "itertools"
 version = "0.12.0"

Cargo.toml

@@ -4,10 +4,12 @@ members = [
     "day-01",
     "day-02",
     "day-03",
-    "day-05"
+    "day-05",
+    "day-06"
 ]
 
 [workspace.dependencies]
+indoc = "2.0.4"
 itertools = "0.12.0"
 nom = "7.1.3"
 rayon = "1.8.0"

day-06/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "day-06"
+version = "0.0.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+indoc.workspace = true
+nom.workspace = true
+rayon.workspace = true

day-06/src/bin/input.txt

@@ -0,0 +1,2 @@
+Time:        46     82     84     79
+Distance:   347   1522   1406   1471

day-06/src/bin/part1.rs

@@ -0,0 +1,68 @@
+use nom::{
+    bytes::complete::tag,
+    character::complete::{self, newline, space1},
+    multi::separated_list1,
+    sequence::{pair, preceded, separated_pair},
+    IResult, Parser,
+};
+
+fn main() {
+    println!("{}", part1(include_str!("./input.txt")));
+}
+
+fn part1(input: &str) -> u64 {
+    separated_pair(time_parser, newline, distance_parser)
+        .map(|(times, distances)| {
+            times
+                .into_iter()
+                .zip(distances)
+                .map(|(time, distance)| calc_game(time, distance) as u64)
+                .product::<u64>()
+        })
+        .parse(input)
+        .unwrap()
+        .1
+}
+
+fn time_parser(i: &str) -> IResult<&str, Vec<u32>> {
+    preceded(
+        pair(tag("Time:"), space1),
+        separated_list1(space1, complete::u32),
+    )(i)
+}
+
+fn distance_parser(i: &str) -> IResult<&str, Vec<u32>> {
+    preceded(
+        pair(tag("Distance:"), space1),
+        separated_list1(space1, complete::u32),
+    )(i)
+}
+
+fn calc_game(time: u32, distance: u32) -> u32 {
+    (1..time)
+        .filter_map(|t| (calc_distance(t, time) > distance).then_some(()))
+        .count() as u32
+}
+
+fn calc_distance(hold_time: u32, total_time: u32) -> u32 {
+    hold_time * (total_time - hold_time)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(
+            part1(indoc!(
+                "
+        Time:      7  15   30
+        Distance:  9  40  200
+        "
+            )),
+            288
+        );
+    }
+}

day-06/src/bin/part2.rs

@@ -0,0 +1,65 @@
+use nom::{
+    bytes::complete::tag,
+    character::complete::{digit1, newline, space1},
+    multi::separated_list1,
+    sequence::{pair, preceded, separated_pair},
+    IResult, Parser,
+};
+use rayon::prelude::*;
+
+fn main() {
+    println!("{}", part2(include_str!("./input.txt")));
+}
+
+fn part2(input: &str) -> u64 {
+    separated_pair(time_parser, newline, distance_parser)
+        .map(|(time, distance)| calc_game(time, distance))
+        .parse(input)
+        .unwrap()
+        .1
+}
+
+fn time_parser(i: &str) -> IResult<&str, u64> {
+    preceded(pair(tag("Time:"), space1), separated_list1(space1, digit1))
+        .map(|strs| strs.join("").parse::<u64>().expect("Invalid digit"))
+        .parse(i)
+}
+
+fn distance_parser(i: &str) -> IResult<&str, u64> {
+    preceded(
+        pair(tag("Distance:"), space1),
+        separated_list1(space1, digit1),
+    )
+    .map(|strs| strs.join("").parse::<u64>().expect("Invalid digit"))
+    .parse(i)
+}
+
+fn calc_game(time: u64, distance: u64) -> u64 {
+    (1..time)
+        .into_par_iter()
+        .filter_map(|t| (calc_distance(t, time) > distance).then_some(()))
+        .count() as u64
+}
+
+fn calc_distance(hold_time: u64, total_time: u64) -> u64 {
+    hold_time * (total_time - hold_time)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(
+            part2(indoc!(
+                "
+        Time:      7  15   30
+        Distance:  9  40  200
+        "
+            )),
+            288
+        );
+    }
+}