Year 2016: Day 19

CHANGELOG.md

@@ -10,6 +10,10 @@ Of note:
 - The changelog 2015.5.2 has been rewritten from each commit content.
 - This file may be amended entirely in the future to adhere to the [GNU Changelog style](https://www.gnu.org/prep/standards/html_node/Style-of-Change-Logs.html#Style-of-Change-Logs)
 
+## [2016.19.1]
+### Added
+- Solved [exercice for 2016, day 19](src/year_2016/19.rs).
+
 ## [2016.18.1]
 ### Added
 - Solved [exercice for 2016, day 18](src/year_2016/18.rs).

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "advent-rs"
-version = "2016.18.1"
+version = "2016.19.1"
 edition = "2021"
 authors = ["Arnaud 'red' Rouyer"]
 readme = "README.md"

NOTES_2016.md

@@ -86,3 +86,7 @@ There was some confusion between all the generics, abstractions, and types, espe
 ## Day 18: Like a Rogue
 
 Easy come, easy go.
+
+## Day 19: An Elephant Named Joseph
+
+As easy in Rust as it was in Ruby.

README.md

@@ -6,7 +6,7 @@ As I said, [Consistency is hard](https://github.com/joshleaves/advent-rb), and I
 
 I'm also adding notes that may be useful if you're (like me) discovering Rust:
 - [2015, complete!](NOTES_2015.md)
-- [2016, up to day 18](NOTES_2016.md)
+- [2016, up to day 19](NOTES_2016.md)
 
 # Regarding style rules
 I'm gonna use a mix of what `cargo fmt` does, with some stuff that feels more natural to me.

benches/year_2016.rs

@@ -16,6 +16,7 @@ use advent_rs::year_2016::day_15;
 use advent_rs::year_2016::day_16;
 use advent_rs::year_2016::day_17;
 use advent_rs::year_2016::day_18;
+use advent_rs::year_2016::day_19;
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
 pub fn year_2016_day_01(c: &mut Criterion) {
@@ -234,6 +235,18 @@ pub fn year_2016_day_18(c: &mut Criterion) {
   g2016_day_18.finish();
 }
 
+pub fn year_2016_day_19(c: &mut Criterion) {
+  let mut g2016_day_19 = c.benchmark_group("year_2016::day_19");
+  let input_year_2016_day_19 = include_str!("../inputs/year_2016/day_19_input");
+  g2016_day_19.bench_function("year_2016::day_19_v1", |b| {
+    b.iter(|| day_19::day_19_v1(black_box(input_year_2016_day_19)))
+  });
+  g2016_day_19.bench_function("year_2016::day_19_v2", |b| {
+    b.iter(|| day_19::day_19_v2(black_box(input_year_2016_day_19)))
+  });
+  g2016_day_19.finish();
+}
+
 criterion_group!(
   benches,
   year_2016_day_01,
@@ -253,6 +266,7 @@ criterion_group!(
   year_2016_day_15,
   year_2016_day_16,
   year_2016_day_17,
-  year_2016_day_18
+  year_2016_day_18,
+  year_2016_day_19
 );
 criterion_main!(benches);

inputs/year_2016/day_19_input

@@ -0,0 +1 @@
+3012210

src/year_2016.rs

@@ -21,6 +21,7 @@ pub mod day_15;
 pub mod day_16;
 pub mod day_17;
 pub mod day_18;
+pub mod day_19;
 
 pub fn solve(day: u8, part: u8, input: impl Into<String>) -> Option<String> {
   if part != 1 && part != 2 {
@@ -45,6 +46,8 @@ pub fn solve(day: u8, part: u8, input: impl Into<String>) -> Option<String> {
     15 => Some(format!("{}", day_15::day_15(part, input))),
     16 => Some(format!("{}", day_16::day_16(part, input))),
     17 => Some(format!("{}", day_17::day_17(part, input))),
+    18 => Some(format!("{}", day_18::day_18(part, input))),
+    19 => Some(format!("{}", day_19::day_19(part, input))),
     _ => None,
   }
 }
@@ -187,4 +190,11 @@ mod tests {
     assert_eq!(day_18::day_18_v1(input), 1926);
     assert_eq!(day_18::day_18_v2(input), 19_986_699);
   }
+
+  #[test]
+  fn day_19() {
+    let input = include_str!("../inputs/year_2016/day_19_input");
+    assert_eq!(day_19::day_19_v1(input), 1_830_117);
+    assert_eq!(day_19::day_19_v2(input), 1_417_887);
+  }
 }

src/year_2016/day_19.rs

@@ -0,0 +1,46 @@
+use itertools::Itertools;
+use std::collections::VecDeque;
+
+pub fn day_19_v1(input: impl Into<String>) -> u32 {
+  let number = input.into().parse::<u32>().unwrap();
+  let mut binary = format!("{number:b}").chars().collect_vec();
+  binary.rotate_left(1);
+
+  u32::from_str_radix(&binary.iter().collect::<String>(), 2).unwrap()
+}
+
+pub fn day_19_v2(input: impl Into<String>) -> u32 {
+  let number = input.into().parse::<u32>().unwrap();
+  let mid = (number + 1) / 2;
+  let mut arr_v1: VecDeque<u32> = (1..mid).collect();
+  let mut arr_v2: VecDeque<u32> = (mid..(number + 1)).collect();
+  loop {
+    if arr_v2.len() >= arr_v1.len() {
+      arr_v2.pop_front();
+      if arr_v2.is_empty() {
+        return arr_v1[0];
+      }
+    } else {
+      arr_v1.pop_back();
+    }
+    arr_v1.push_back(arr_v2.pop_front().unwrap());
+    arr_v2.push_back(arr_v1.pop_front().unwrap());
+  }
+}
+
+solvable!(day_19, day_19_v1, day_19_v2, u32);
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn works_with_samples_v1() {
+    assert_eq!(day_19_v1("5"), 3);
+  }
+
+  #[test]
+  fn works_with_samples_v2() {
+    assert_eq!(day_19_v2("5"), 2);
+  }
+}