[2025] Day 1 first solutions

Author: connorslade

README.md

@@ -5,6 +5,7 @@ Thank you to [Eric Wastl](http://was.tl) for running this incredible yearly even
 
 ## [2025](https://adventofcode.com/2025) [![aoc_2025](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2025.yml/badge.svg)](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2025.yml)
 
+- [Day 01: Secret Entrance](aoc_2025/src/day_01.rs)
 <!-- MARKER -->
 
 ## [2024](https://adventofcode.com/2024) [![aoc_2024](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2024.yml/badge.svg)](https://github.com/connorslade/advent-of-code/actions/workflows/aoc_2024.yml)

aoc_2025/src/day_01.rs

@@ -0,0 +1,92 @@
+use common::{Answer, solution};
+
+solution!("Secret Entrance", 1);
+
+fn part_a(input: &str) -> Answer {
+    let mut pos = 50;
+    let mut out = 0;
+
+    for line in input.trim().lines() {
+        let num = line[1..].parse::<u32>().unwrap();
+        match line.as_bytes()[0] {
+            b'L' => {
+                if num % 100 > pos {
+                    pos = 100 - (num % 100 - pos);
+                } else {
+                    pos -= num;
+                }
+            }
+            b'R' => pos = (pos + num) % 100,
+            _ => unreachable!(),
+        }
+
+        out += (pos == 0) as u64;
+    }
+
+    out.into()
+}
+
+fn part_b(input: &str) -> Answer {
+    let mut pos = 50;
+    let mut out = 0;
+
+    for line in input.trim().lines() {
+        let num = line[1..].parse::<u32>().unwrap();
+        match line.as_bytes()[0] {
+            b'L' => {
+                for _ in 0..num {
+                    if pos == 0 {
+                        pos = 99;
+                    } else {
+                        pos -= 1;
+                    }
+
+                    out += (pos == 0) as u64;
+                }
+            }
+            b'R' => {
+                for _ in 0..num {
+                    if pos == 99 {
+                        pos = 0;
+                    } else {
+                        pos += 1;
+                    }
+
+                    out += (pos == 0) as u64;
+                }
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    out.into()
+}
+
+#[cfg(test)]
+mod test {
+    use indoc::indoc;
+
+    const CASE: &str = indoc! {"
+        L68
+        L30
+        R48
+        L5
+        R60
+        L55
+        L1
+        L99
+        R14
+        L82
+
+    "};
+
+    #[test]
+    fn part_a() {
+        assert_eq!(super::part_a(CASE), 3.into());
+    }
+
+    #[test]
+    fn part_b() {
+        assert_eq!(super::part_b(CASE), 6.into());
+    }
+}

aoc_2025/src/lib.rs

@@ -1,7 +1,9 @@
 use common::Solution;
 
+mod day_01;
 // [import_marker]
 
 pub const SOLUTIONS: &[Solution] = &[
+    day_01::SOLUTION,
     // [list_marker]
 ];