Year 2025 Day 1

Author: maneatingape

README.md

@@ -1,6 +1,6 @@
 # Advent of Code [![checks-badge]][checks-link] [![docs-badge]][docs-link]
 
-Blazing fast Rust solutions for every [Advent of Code] puzzle from 2015 to 2024, taking
+*2025 in progress!* Blazing fast Rust solutions for every [Advent of Code] puzzle from 2015 to 2024, taking
 **470 milliseconds** to solve all 500 stars. Each solution is carefully optimized for performance
 while ensuring the code remains concise, readable, and idiomatic.
 
@@ -65,10 +65,20 @@ Performance is reasonable even on older hardware, for example a 2011 MacBook Pro
 
 ![pie-all]
 
+| Year | [2025](#2025) |
+| --- | --- |
+| Benchmark (ms) | WIP |
+
 | Year | [2015](#2015) | [2016](#2016) | [2017](#2017) | [2018](#2018) | [2019](#2019) | [2020](#2020) | [2021](#2021) | [2022](#2022) | [2023](#2023) | [2024](#2024) |
 | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | Benchmark (ms) | 14 | 109 | 57 | 35 | 13 | 220 | 8 | 5 | 5 | 4 |
 
+## 2025
+
+| Day | Problem | Solution | Benchmark (μs) |
+| --- | --- | --- | --: |
+| 1 | [Secret Entrance](https://adventofcode.com/2025/day/1) | [Source](src/year2025/day01.rs) | 47 |
+
 ## 2024
 
 ![pie-2024]

benches/benchmark.rs

@@ -93,3 +93,7 @@ benchmark!(year2024
     day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
     day14, day15, day16, day17, day18, day19, day20, day21, day22, day23, day24, day25
 );
+
+benchmark!(year2025
+    day01
+);

src/lib.rs

@@ -72,3 +72,7 @@ library!(year2024 "Locate the Chief Historian in time for the big Christmas slei
     day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
     day14, day15, day16, day17, day18, day19, day20, day21, day22, day23, day24, day25
 );
+
+library!(year2025 "???"
+    day01
+);

src/main.rs

@@ -27,6 +27,7 @@ fn main() {
         year2022(),
         year2023(),
         year2024(),
+        year2025(),
     ];
 
     // Run selected solutions.
@@ -138,3 +139,7 @@ run!(year2024
     day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
     day14, day15, day16, day17, day18, day19, day20, day21, day22, day23, day24, day25
 );
+
+run!(year2025
+    day01
+);

src/year2025/day01.rs

@@ -0,0 +1,35 @@
+use crate::util::parse::*;
+
+pub fn parse(input: &str) -> Vec<i32> {
+    let direction = input.bytes().filter(|&b| b.is_ascii_uppercase());
+    let amount = input.iter_signed::<i32>();
+    direction.zip(amount).map(|(d, a)| if d == b'R' { a } else { -a }).collect()
+}
+
+pub fn part1(input: &[i32]) -> i32 {
+    let mut dial: i32 = 50;
+    let mut password = 0;
+
+    for &delta in input {
+        dial += delta;
+        password += i32::from(dial % 100 == 0);
+    }
+
+    password
+}
+
+pub fn part2(input: &[i32]) -> i32 {
+    let mut dial: i32 = 50;
+    let mut password = 0;
+
+    for &delta in input {
+        if delta >= 0 {
+            password += (dial + delta) / 100;
+        } else {
+            password += (100 - dial - delta) / 100 - (100 - dial) / 100;
+        }
+        dial = (dial + delta).rem_euclid(100);
+    }
+
+    password
+}

tests/test.rs

@@ -85,3 +85,7 @@ test!(year2024
     day01, day02, day03, day04, day05, day06, day07, day08, day09, day10, day11, day12, day13,
     day14, day15, day16, day17, day18, day19, day20, day21, day22, day23, day24, day25
 );
+
+test!(year2025
+    day01
+);

tests/year2025/day01.rs

@@ -0,0 +1,25 @@
+use aoc::year2025::day01::*;
+
+const EXAMPLE: &str = "\
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82";
+
+#[test]
+fn part1_test() {
+    let input = parse(EXAMPLE);
+    assert_eq!(part1(&input), 3);
+}
+
+#[test]
+fn part2_test() {
+    let input = parse(EXAMPLE);
+    assert_eq!(part2(&input), 6);
+}