Year 2015 Day 14

Author: maneatingape

README.md

@@ -249,3 +249,4 @@ pie
 | 11 | [Corporate Policy](https://adventofcode.com/2015/day/11) | [Source](src/year2015/day11.rs) | 1 |
 | 12 | [JSAbacusFramework.io](https://adventofcode.com/2015/day/12) | [Source](src/year2015/day12.rs) | 80 |
 | 13 | [Knights of the Dinner Table](https://adventofcode.com/2015/day/13) | [Source](src/year2015/day13.rs) | 39 |
+| 14 | [Reindeer Olympics](https://adventofcode.com/2015/day/14) | [Source](src/year2015/day14.rs) | 28 |

benches/benchmark.rs

@@ -49,6 +49,7 @@ mod year2015 {
     benchmark!(year2015, day11);
     benchmark!(year2015, day12);
     benchmark!(year2015, day13);
+    benchmark!(year2015, day14);
 }
 
 mod year2019 {

input/year2015/day14.txt

@@ -0,0 +1,9 @@
+Vixen can fly 8 km/s for 8 seconds, but then must rest for 53 seconds.
+Blitzen can fly 13 km/s for 4 seconds, but then must rest for 49 seconds.
+Rudolph can fly 20 km/s for 7 seconds, but then must rest for 132 seconds.
+Cupid can fly 12 km/s for 4 seconds, but then must rest for 43 seconds.
+Donner can fly 9 km/s for 5 seconds, but then must rest for 38 seconds.
+Dasher can fly 10 km/s for 4 seconds, but then must rest for 37 seconds.
+Comet can fly 3 km/s for 37 seconds, but then must rest for 76 seconds.
+Prancer can fly 9 km/s for 12 seconds, but then must rest for 97 seconds.
+Dancer can fly 37 km/s for 1 seconds, but then must rest for 36 seconds.

src/lib.rs

@@ -173,6 +173,7 @@ pub mod year2015 {
     pub mod day11;
     pub mod day12;
     pub mod day13;
+    pub mod day14;
 }
 
 /// # Rescue Santa from deep space with a solar system adventure.

src/main.rs

@@ -89,6 +89,7 @@ fn all_solutions() -> Vec<Solution> {
         solution!(year2015, day11),
         solution!(year2015, day12),
         solution!(year2015, day13),
+        solution!(year2015, day14),
         // 2019
         solution!(year2019, day01),
         solution!(year2019, day02),

src/year2015/day14.rs

@@ -0,0 +1,55 @@
+//! # Reindeer Olympics
+//!
+//! In order to make things easier we create a function to calculate the distance travelled by a
+//! reindeer at any arbitrary time.
+use crate::util::iter::*;
+use crate::util::parse::*;
+
+type Reindeer = [u32; 3];
+
+pub fn parse(input: &str) -> Vec<Reindeer> {
+    input.iter_unsigned().chunk::<3>().collect()
+}
+
+pub fn part1(input: &[Reindeer]) -> u32 {
+    part1_testable(input, 2503)
+}
+
+pub fn part2(input: &[Reindeer]) -> u32 {
+    part2_testable(input, 2503)
+}
+
+pub fn part1_testable(input: &[Reindeer], time: u32) -> u32 {
+    input.iter().map(|&r| distance(r, time)).max().unwrap()
+}
+
+pub fn part2_testable(input: &[Reindeer], time: u32) -> u32 {
+    let mut score = vec![0; input.len()];
+    let mut distances = vec![0; input.len()];
+
+    for minute in 1..time {
+        let mut lead = 0;
+
+        for (index, &reindeer) in input.iter().enumerate() {
+            let next = distance(reindeer, minute);
+            distances[index] = next;
+            lead = lead.max(next);
+        }
+
+        for (index, &distance) in distances.iter().enumerate() {
+            if distance == lead {
+                score[index] += 1;
+            }
+        }
+    }
+
+    *score.iter().max().unwrap()
+}
+
+fn distance([speed, fly, rest]: Reindeer, time: u32) -> u32 {
+    let total = fly + rest;
+    let complete = time / total;
+    let partial = (time % total).min(fly);
+
+    speed * (fly * complete + partial)
+}

tests/test.rs

@@ -42,6 +42,7 @@ mod year2015 {
     mod day11_test;
     mod day12_test;
     mod day13_test;
+    mod day14_test;
 }
 
 mod year2019 {

tests/year2015/day14_test.rs

@@ -0,0 +1,17 @@
+use aoc::year2015::day14::*;
+
+const EXAMPLE: &str = "\
+Comet can fly 14 km/s for 10 seconds, but then must rest for 127 seconds.
+Dancer can fly 16 km/s for 11 seconds, but then must rest for 162 seconds.";
+
+#[test]
+fn part1_test() {
+    let input = parse(EXAMPLE);
+    assert_eq!(part1_testable(&input, 1000), 1120);
+}
+
+#[test]
+fn part2_test() {
+    let input = parse(EXAMPLE);
+    assert_eq!(part2_testable(&input, 1000), 689);
+}