1 files changed, 96 insertions, 0 deletions
diff --git a/2025/d1.rs b/2025/d1.rs
new file mode 100644
index 0000000..48209ef
--- /dev/null
+++ b/2025/d1.rs
@@ -0,0 +1,96 @@
+use aoc::fetch::fetch;
+
+#[derive(Debug)]
+struct Ring {
+    inner: usize,
+    counter: usize,
+}
+
+impl Ring {
+    fn new() -> Self {
+        Self {
+            inner: 50,
+            counter: Default::default(),
+        }
+    }
+
+    const MAX: usize = 99;
+
+    fn left(&mut self, num: usize, count_each_step: bool) {
+        for _ in 0..num {
+            if self.inner == 0 {
+                self.inner = Self::MAX;
+            } else {
+                self.inner -= 1;
+            }
+            if count_each_step {
+                self.check_counter();
+            }
+        }
+        if !count_each_step {
+            self.check_counter();
+        }
+    }
+
+    fn right(&mut self, num: usize, count_each_step: bool) {
+        for _ in 0..num {
+            if self.inner == Self::MAX {
+                self.inner = 0;
+            } else {
+                self.inner += 1;
+            }
+            if count_each_step {
+                self.check_counter();
+            }
+        }
+        if !count_each_step {
+            self.check_counter();
+        }
+    }
+
+    fn check_counter(&mut self) {
+        if self.inner == 0 {
+            self.counter += 1;
+        }
+    }
+}
+
+fn solve(count_each_step: bool) -> usize {
+    let mut ring = Ring::new();
+    let input = fetch(
+        1, '\n',
+    );
+    for i in input {
+        if i.is_empty() {
+            continue;
+        }
+        let dir = i
+            .chars()
+            .next()
+            .unwrap();
+        let num = i[1..]
+            .parse()
+            .unwrap();
+
+        match dir {
+            'L' => ring.left(
+                num,
+                count_each_step,
+            ),
+            'R' => ring.right(
+                num,
+                count_each_step,
+            ),
+            _ => {}
+        }
+    }
+    ring.counter
+}
+
+pub fn part1() -> usize {
+    solve(false)
+}
+
+pub fn part2() -> usize {
+    solve(true)
+}