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

src/lib.rs

@@ -1,2 +1,5 @@
+#[macro_use]
+extern crate scan_fmt;
+
 mod common;
 pub mod solvers;

src/main.rs

@@ -2,7 +2,7 @@ use advent_of_code_2025::solvers;
 
 fn main() {
     println!("### Advent of Code 2025 ###\n");
-    // SecretEntrance
+    solvers::run(solvers::secret_entrance::SecretEntrance {});
     // GiftShop
     // Lobby
     solvers::run(solvers::printing_department::PrintingDepartment {});
@@ -11,4 +11,7 @@ fn main() {
     // Laboratories
     solvers::run(solvers::playground::Playground::new(None));
     solvers::run(solvers::movie_theater::MovieTheater {});
+    // Factory
+    // Reactor
+    // ChristmasTreeFarm
 }

src/solvers.rs

@@ -9,6 +9,7 @@ pub mod cafeteria;
 pub mod movie_theater;
 pub mod playground;
 pub mod printing_department;
+pub mod secret_entrance;
 pub mod trash_compactor;
 
 pub trait Solver {

src/solvers/secret_entrance.rs

@@ -0,0 +1,42 @@
+use crate::solvers::Solver;
+use std::io::BufRead;
+
+pub struct SecretEntrance {}
+
+impl SecretEntrance {
+    const START_POSITION: i32 = 50;
+    const DIAL_SIZE: i32 = 100;
+    const COUNT_POSITION: i32 = 0;
+    const POSITIVE_SIGN_CHAR: char = 'R';
+    const NEGATIVE_SIGN_CHAR: char = 'L';
+}
+
+impl Solver for SecretEntrance {
+    const PUZZLE_INDEX: u8 = 1;
+    const PUZZLE_NAME: &'static str = "Secret Entrance";
+
+    fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64) {
+        let mut position = Self::START_POSITION;
+        let mut count = 0;
+        let format = 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) {
+                position = (position
+                    + if sign == Self::POSITIVE_SIGN_CHAR {
+                        distance
+                    } else {
+                        -distance
+                    })
+                .rem_euclid(Self::DIAL_SIZE);
+            }
+            if position == Self::COUNT_POSITION {
+                count = count + 1;
+            }
+        }
+        (count, 0)
+    }
+}