Year 2019 Day 1

README.md

@@ -65,7 +65,7 @@ pie
 * [2022](#2022) (19 ms)
 * [2021](#2021) (11 ms)
 * [2020](#2020) (286 ms)
-* [2015](#2015) (in progress)
+* [Earlier](#2019) (in progress)
 
 ## 2022
 
@@ -189,6 +189,12 @@ pie
 | 24 | [Lobby Layout](https://adventofcode.com/2020/day/24) | [Source](src/year2020/day24.rs) | 4346 |
 | 25 | [Combo Breaker](https://adventofcode.com/2020/day/25) | [Source](src/year2020/day25.rs) | 24 |
 
+## 2019
+
+| Day | Problem | Solution | Benchmark (μs) |
+| --- | --- | --- | --: |
+| 1 | [The Tyranny of the Rocket Equation](https://adventofcode.com/2019/day/1) | [Source](src/year2019/day01.rs) | 1 |
+
 ## 2015
 
 | Day | Problem | Solution | Benchmark (μs) |

benches/benchmark.rs

@@ -119,6 +119,10 @@ mod year2020 {
     benchmark!(year2020, day25);
 }
 
+mod year2019 {
+    benchmark!(year2019, day01);
+}
+
 mod year2015 {
     benchmark!(year2015, day01);
     benchmark!(year2015, day02);

input/year2019/day01.txt

@@ -0,0 +1,100 @@
+73617
+104372
+131825
+85022
+105514
+78478
+87420
+118553
+97680
+89479
+146989
+79746
+108085
+117895
+143811
+102509
+102382
+92975
+72978
+94208
+130521
+83042
+138605
+107566
+63374
+71176
+129487
+118408
+115425
+63967
+98282
+121829
+92834
+61084
+70122
+87221
+132773
+141347
+133225
+81199
+94994
+60881
+110074
+63499
+143107
+76618
+86818
+135394
+106908
+96085
+99801
+112903
+51751
+56002
+70924
+62180
+133025
+68025
+122660
+64898
+77339
+62109
+133891
+134460
+84224
+54836
+59748
+125540
+67796
+71845
+92899
+130103
+74612
+136820
+96212
+132002
+97405
+82629
+63717
+62805
+112693
+147810
+139827
+116220
+69711
+50236
+137833
+103743
+147456
+112098
+84867
+75615
+132738
+81072
+89444
+58443
+94465
+112494
+82127
+132533

src/lib.rs

@@ -171,6 +171,11 @@ pub mod year2020 {
     pub mod day25;
 }
 
+/// # Rescue Santa from deep space with a solar system adventure.
+pub mod year2019 {
+    pub mod day01;
+}
+
 /// # Help Santa by solving puzzles to fix the weather machine's snow function.
 pub mod year2015 {
     pub mod day01;

src/main.rs

@@ -159,6 +159,8 @@ fn all_solutions() -> Vec<Solution> {
         solution!(year2020, day23),
         solution!(year2020, day24),
         solution!(year2020, day25),
+        // 2019
+        solution!(year2019, day01),
         // 2015
         solution!(year2015, day01),
         solution!(year2015, day02),

src/year2019/day01.rs

@@ -0,0 +1,34 @@
+//! # The Tyranny of the Rocket Equation
+//!
+//! The title of the problem is a reference to the
+//! [real life equation](https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation).
+use crate::util::parse::*;
+
+/// The [`iter_unsigned`] utility method extracts and parses numbers from surrounding text.
+///
+/// [`iter_unsigned`]: crate::util::parse
+pub fn parse(input: &str) -> Vec<u32> {
+    input.iter_unsigned().collect()
+}
+
+/// Calculate fuel requirements following the formula.
+pub fn part1(input: &[u32]) -> u32 {
+    input.iter().map(|mass| mass / 3 - 2).sum()
+}
+
+/// Calculate the fuel requirements taking into account that fuel needs more fuel to lift it.
+/// Mass of 8 or below results in zero or negative fuel so we can stop.
+pub fn part2(input: &[u32]) -> u32 {
+    input
+        .iter()
+        .copied()
+        .map(|mut mass| {
+            let mut fuel = 0;
+            while mass > 8 {
+                mass = mass / 3 - 2;
+                fuel += mass;
+            }
+            fuel
+        })
+        .sum()
+}

tests/test.rs

@@ -82,6 +82,10 @@ mod year2020 {
     mod day25_test;
 }
 
+mod year2019 {
+    mod day01_test;
+}
+
 mod year2015 {
     mod day01_test;
     mod day02_test;

tests/year2019/day01_test.rs

@@ -0,0 +1,15 @@
+use aoc::year2019::day01::*;
+
+const EXAMPLE: &str = "100756";
+
+#[test]
+fn part1_test() {
+    let input = parse(EXAMPLE);
+    assert_eq!(part1(&input), 33583);
+}
+
+#[test]
+fn part2_test() {
+    let input = parse(EXAMPLE);
+    assert_eq!(part2(&input), 50346);
+}