AoC 2025 Day 1 - rust

Author: pareronia

README.md

@@ -13,6 +13,7 @@
 | python3 | [✓](src/main/python/AoC2025_01.py) | [✓](src/main/python/AoC2025_02.py) | [✓](src/main/python/AoC2025_03.py) | [✓](src/main/python/AoC2025_04.py) | [✓](src/main/python/AoC2025_05.py) | [✓](src/main/python/AoC2025_06.py) | [✓](src/main/python/AoC2025_07.py) | [✓](src/main/python/AoC2025_08.py) | [✓](src/main/python/AoC2025_09.py) | [✓](src/main/python/AoC2025_10.py) | [✓](src/main/python/AoC2025_11.py) | [✓](src/main/python/AoC2025_12.py) |
 | java | [✓](src/main/java/AoC2025_01.java) | [✓](src/main/java/AoC2025_02.java) | [✓](src/main/java/AoC2025_03.java) | [✓](src/main/java/AoC2025_04.java) | [✓](src/main/java/AoC2025_05.java) | [✓](src/main/java/AoC2025_06.java) | [✓](src/main/java/AoC2025_07.java) | [✓](src/main/java/AoC2025_08.java) | [✓](src/main/java/AoC2025_09.java) | [✓](src/main/java/AoC2025_10.java) | [✓](src/main/java/AoC2025_11.java) | [✓](src/main/java/AoC2025_12.java) |
 | bash | [✓](src/main/bash/AoC2025_01.sh) | [✓](src/main/bash/AoC2025_02.sh) | [✓](src/main/bash/AoC2025_03.sh) | [✓](src/main/bash/AoC2025_04.sh) | [✓](src/main/bash/AoC2025_05.sh) | [✓](src/main/bash/AoC2025_06.sh) | [✓](src/main/bash/AoC2025_07.sh) | | | | [✓](src/main/bash/AoC2025_11.sh) | [✓](src/main/bash/AoC2025_12.sh) |
+| rust | [✓](src/main/rust/AoC2025_01/src/main.rs) | | | | | | | | | | | |
 <!-- @END:ImplementationsTable:2025@ -->
 
 ## 2024

src/main/rust/AoC2025_01/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "AoC2025_01"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }

src/main/rust/AoC2025_01/src/main.rs

@@ -0,0 +1,110 @@
+#![allow(non_snake_case)]
+
+use aoc::Puzzle;
+
+const START: isize = 50;
+const TOTAL: isize = 100;
+
+enum Count {
+ LandedOnZero,
+ PassedByZero,
+}
+
+impl Count {
+ fn count(&self, dial: isize, rotation: isize) -> usize {
+ match self {
+ Count::LandedOnZero => {
+ if (dial + rotation) % TOTAL == 0 {
+ 1
+ } else {
+ 0
+ }
+ }
+ Count::PassedByZero => {
+ if rotation >= 0 {
+ ((dial + rotation) / TOTAL) as usize
+ } else {
+ (((TOTAL - dial) % TOTAL - rotation) / TOTAL) as usize
+ }
+ }
+ }
+ }
+}
+
+struct AoC2025_01;
+
+impl AoC2025_01 {
+ fn solve(&self, rotations: &[isize], count: Count) -> usize {
+ let mut dial = START;
+ let mut ans = 0;
+ rotations.iter().for_each(|rotation| {
+ ans += count.count(dial, *rotation);
+ dial = (dial + *rotation).rem_euclid(TOTAL);
+ });
+ ans
+ }
+}
+
+impl aoc::Puzzle for AoC2025_01 {
+ type Input = Vec<isize>;
+ type Output1 = usize;
+ type Output2 = usize;
+
+ aoc::puzzle_year_day!(2025, 1);
+
+ fn parse_input(&self, lines: Vec<String>) -> Self::Input {
+ lines
+ .iter()
+ .map(|line| {
+ let s = match line.chars().nth(0).unwrap() {
+ 'R' => 1,
+ 'L' => -1,
+ _ => panic!(),
+ };
+ s * line[1..].parse::<isize>().unwrap()
+ })
+ .collect::<Vec<_>>()
+ }
+
+ fn part_1(&self, rotations: &Self::Input) -> Self::Output1 {
+ self.solve(rotations, Count::LandedOnZero)
+ }
+
+ fn part_2(&self, rotations: &Self::Input) -> Self::Output2 {
+ self.solve(rotations, Count::PassedByZero)
+ }
+
+ fn samples(&self) {
+ aoc::puzzle_samples! {
+ self, part_1, TEST, 3,
+ self, part_2, TEST, 6
+ };
+ }
+}
+
+fn main() {
+ AoC2025_01 {}.run(std::env::args());
+}
+
+const TEST: &str = "\
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82
+";
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ pub fn samples() {
+ AoC2025_01 {}.samples();
+ }
+}