From c1700fda5f6faf77dab74b3b6090f503333722df Mon Sep 17 00:00:00 2001
From: Rakarake <raka@rakarake.xyz>
Date: Mon, 1 Dec 2025 13:36:43 +0100
Subject: [PATCH] 2025 day1 part1

---
 aoc2025/day1.rs | 57 +++++++++++++++++++++++++++++++++++++++++++++++++
 utils/lib.rs    |  7 ++++++
 2 files changed, 64 insertions(+)
 create mode 100644 aoc2025/day1.rs

diff --git a/aoc2025/day1.rs b/aoc2025/day1.rs
new file mode 100644
index 0000000..6022f38
--- /dev/null
+++ b/aoc2025/day1.rs
@@ -0,0 +1,57 @@
+use utils::load_string;
+
+const TEST_INPUT: &str = 
+"L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82";
+
+const START: u32 = 50;
+
+enum Rotation {
+    Left(u32),
+    Right(u32),
+}
+
+fn parse(input: &str) -> Vec<Rotation> {
+    input.lines().map(|l| {
+            let (indicator, number) = l.split_at(1);
+            match indicator {
+                "L" => Rotation::Left(number.parse().unwrap()),
+                "R" => Rotation::Right(number.parse().unwrap()),
+            _ => panic!("hey!")
+        }
+    }).collect()
+}
+
+pub fn part1() -> u32 {
+    let input = &load_string("inputs/2025/day1.input");
+    //let input = TEST_INPUT;
+    let mut current_rotation = START;
+    let mut result: u32 = 0;
+    for roation in parse(input).iter() {
+        match roation {
+            Rotation::Left(amount) => {
+                // overflows to the left
+                current_rotation = (((current_rotation as i32) - *amount as i32).rem_euclid(100)) as u32;
+            },
+            Rotation::Right(amount) => {
+                // overflows to the right
+                current_rotation = (((current_rotation as i32) + *amount as i32).rem_euclid(100)) as u32;
+            },
+        }
+        if current_rotation == 0 {
+            result += 1;
+        }
+    }
+    result
+}
+pub fn part2() -> u32 {
+    0
+}
diff --git a/utils/lib.rs b/utils/lib.rs
index 3dad11a..9b8f35e 100644
--- a/utils/lib.rs
+++ b/utils/lib.rs
@@ -1,3 +1,10 @@
+use std::path::Path;
+
+// Yoinked from https://github.com/loafey/advent_of_code/blob/master/utils/lib.rs
+pub fn load_string<P: AsRef<Path>>(p: P) -> String {
+    std::fs::read_to_string(&p).unwrap_or_else(|_| panic!("failed to load {:?}", p.as_ref()))
+}
+
 pub trait Matrix {
     fn transpose(self) -> Self;
     fn reverse_rows(self) -> Self;