Add solution for "Day 1: Secret Entrance", part 2

README.md

@@ -1,6 +1,6 @@
 # AdventOfCode2025
 
-Solver for Advent of Code 2025 puzzles. https://adventofcode.com/2025/
+Solver for Advent of Code 2025 puzzles. <https://adventofcode.com/2025/>
 
 This is a single command line application for the puzzles written in [Rust](https://rust-lang.org/).
 
@@ -10,6 +10,12 @@ This project does not contain the puzzle or example inputs as per the [copyright
 
 ## Solutions
 
+### Day 1: Secret Entrance
+
+:mag_right: Puzzle: <https://adventofcode.com/2025/day/1>, :white_check_mark: Solver: [`SecretEntrance`](src/solvers/secret_entrance.rs)
+
+For this one, we are moving around a dial with some not too complicated modulo calculations.
+
 ### Day 4: Printing Department
 
 :mag_right: Puzzle: <https://adventofcode.com/2025/day/4>, :white_check_mark: Solver: [`PrintingDepartment`](src/solvers/printing_department.rs)
@@ -36,7 +42,7 @@ The package contains unit tests for each solver to help troubleshoot issues and
 
 ## License
 
-Copyright (C) 2025 Stefan Müller
+Copyright (C) 2025-2026 Stefan Müller
 
 This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
 

src/solvers/secret_entrance.rs

@@ -6,9 +6,30 @@ pub struct SecretEntrance {}
 impl SecretEntrance {
     const START_POSITION: i32 = 50;
     const DIAL_SIZE: i32 = 100;
-    const COUNT_POSITION: i32 = 0;
+    const ZERO_POSITION: i32 = 0;
     const POSITIVE_SIGN_CHAR: char = 'R';
     const NEGATIVE_SIGN_CHAR: char = 'L';
+
+    fn update_position(
+        position: i32,
+        distance: i32,
+        mut zero_hits: u64,
+        mut zero_passes: u64,
+    ) -> (i32, u64, u64) {
+        let mut new_position = position + distance;
+        let rounds = new_position.div_euclid(Self::DIAL_SIZE);
+        zero_passes += u64::try_from(rounds.abs()).unwrap();
+        new_position -= Self::DIAL_SIZE * rounds;
+        if new_position == Self::ZERO_POSITION {
+            zero_hits += 1;
+            if position != Self::ZERO_POSITION && distance < 0 {
+                zero_passes += 1;
+            }
+        } else if position == Self::ZERO_POSITION && distance < 0 {
+            zero_passes -= 1;
+        }
+        (new_position, zero_hits, zero_passes)
+    }
 }
 
 impl Solver for SecretEntrance {
@@ -17,26 +38,26 @@ impl Solver for SecretEntrance {
 
     fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64) {
         let mut position = Self::START_POSITION;
-        let mut count = 0;
+        let mut zero_hits = 0;
-        let format = format!(
+        let mut zero_passes = 0;
+        let format: String = format!(
             "{{[{}{}]}}{{d}}",
             Self::POSITIVE_SIGN_CHAR,
             Self::NEGATIVE_SIGN_CHAR
         );
         for line in reader.lines().map_while(Result::ok) {
-            if let Ok((sign, distance)) = scan_fmt!(&line, &format, char, i32) {
+            let (sign, distance) = scan_fmt!(&line, &format, char, i32).unwrap();
-                position = (position
+            (position, zero_hits, zero_passes) = Self::update_position(
-                    + if sign == Self::POSITIVE_SIGN_CHAR {
+                position,
-                        distance
+                if sign == Self::POSITIVE_SIGN_CHAR {
-                    } else {
+                    distance
-                        -distance
+                } else {
-                    })
+                    -distance
-                .rem_euclid(Self::DIAL_SIZE);
+                },
-            }
+                zero_hits,
-            if position == Self::COUNT_POSITION {
+                zero_passes,
-                count = count + 1;
+            );
-            }
         }
-        (count, 0)
+        (zero_hits, zero_passes)
     }
 }

tests/examples.rs

@@ -11,7 +11,7 @@ const EXAMPLE_PATHS: &'static [&'static str] = &[
 #[test]
 fn secret_entrance() {
     assert_eq!(
-        Ok((3, 0)),
+        Ok((3, 6)),
         solvers::run_solver(solvers::secret_entrance::SecretEntrance {}, &EXAMPLE_PATHS)
     );
 }

tests/full_data.rs

@@ -3,7 +3,7 @@ use advent_of_code_2025::*;
 #[test]
 fn secret_entrance() {
     assert_eq!(
-        Ok((1086, 0)),
+        Ok((1086, 6268)),
         solvers::run_solver(
             solvers::secret_entrance::SecretEntrance {},
             &solvers::DATA_PATHS