diff --git a/day12/src/lib.rs b/day12/src/lib.rs
new file mode 100644
index 0000000..ec502b3
--- /dev/null
+++ b/day12/src/lib.rs
@@ -0,0 +1,287 @@
+mod node;
+use core::fmt;
+use node::Node;
+
+use aoc_shared::enums::Direction;
+use aoc_shared::grid::Grid as BaseGrid;
+use aoc_shared::impl_grid_newtype;
+
+#[derive(Debug, Copy, Clone, PartialEq)]
+enum CellType {
+    Start,
+    End,
+    Waypoint(u8),
+}
+
+#[derive(Debug, Clone)]
+struct Cell {
+    kind: CellType,
+    idx: usize,
+    coord: (usize, usize),
+}
+
+impl Cell {
+    pub fn new(kind: CellType, idx: usize, coord: (usize, usize)) -> Self {
+        Cell { kind, idx, coord }
+    }
+
+    pub fn get_height(&self) -> u8 {
+        match self.kind {
+            CellType::Start => 0,
+            CellType::End => 25,
+            CellType::Waypoint(c) => c,
+        }
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+pub struct Grid<T>(BaseGrid<T>);
+impl_grid_newtype!(Grid, BaseGrid<Cell>, Cell);
+
+impl Grid<Cell> {
+    pub fn from_file_str(file_str: &str) -> Self {
+        let first_line = file_str.lines().next().unwrap();
+        let width = first_line.len();
+
+        let mut grid = Grid::new(width);
+        let mut idx = 0usize;
+
+        for c in file_str.chars() {
+            let kind = match c {
+                'S' => CellType::Start,
+                'E' => CellType::End,
+                'a'..='z' => CellType::Waypoint(c as u8 - b'a'),
+                '\r' | '\n' => continue,
+                _ => panic!("Invalid character: {c}"),
+            };
+
+            let (x, y) = (idx % width, idx / width);
+            let cell = Cell::new(kind, idx, (x, y));
+
+            grid.vec.push(cell);
+
+            idx += 1;
+        }
+
+        grid
+    }
+
+    fn find_pos(&self, value: CellType) -> Option<usize> {
+        self.vec.iter().position(|item| item.kind == value)
+    }
+
+    pub fn print(&self) {
+        for r in 0usize..self.num_rows() {
+            let range = self.row_first_idx(r)..=self.row_last_idx(r);
+            let line: String = self.vec[range]
+                .iter()
+                .map(|n| (n.get_height() + b'a') as char)
+                .collect();
+
+            println!("{}", line);
+        }
+    }
+
+    fn get_index_for_move(&self, from: usize, dir: Direction) -> Option<usize> {
+        let (mut x, mut y) = self.idx_xy(from);
+
+        match dir {
+            Direction::Up => {
+                if y >= 1 {
+                    y -= 1;
+                } else {
+                    return None;
+                }
+            }
+            Direction::Down => {
+                if y < self.num_rows() - 1 {
+                    y += 1;
+                } else {
+                    return None;
+                }
+            }
+            Direction::Left => {
+                if x >= 1 {
+                    x -= 1;
+                } else {
+                    return None;
+                }
+            }
+            Direction::Right => {
+                if x < self.num_cols() - 1 {
+                    x += 1;
+                } else {
+                    return None;
+                }
+            }
+        };
+
+        Some(self.xy_idx(x, y))
+    }
+
+    fn is_valid_move(&self, start: usize, end: usize) -> bool {
+        // Is the item within the grid?
+        let start_char = self.get(start);
+        let end_char = self.get(end);
+        if start_char.is_none() || end_char.is_none() {
+            return false;
+        }
+
+        let start_char = start_char.unwrap();
+        let end_char = end_char.unwrap();
+        let start_elevation = start_char.get_height();
+        let end_elevation = end_char.get_height();
+        if (end_elevation < start_elevation) || end_elevation.abs_diff(start_elevation) > 1 {
+            return false;
+        }
+
+        let ((start_x, start_y), (end_x, end_y)) = (start_char.coord, end_char.coord);
+        let x_diff = end_x.abs_diff(start_x);
+        let y_diff = end_y.abs_diff(start_y);
+
+        // Have we moved 0 or 1 in a cardinal direction?
+        matches!((x_diff, y_diff), (0, 0) | (0, 1) | (1, 0))
+    }
+
+    fn find_moves(&self, start: usize) -> Vec<usize> {
+        [
+            Direction::Up,
+            Direction::Down,
+            Direction::Left,
+            Direction::Right,
+        ]
+        .into_iter()
+        .filter_map(|d| self.get_index_for_move(start, d))
+        .collect()
+    }
+
+    fn find_valid_moves(&self, start: usize) -> Vec<usize> {
+        self.find_moves(start)
+            .into_iter()
+            .filter(|m| self.is_valid_move(start, *m))
+            .collect()
+    }
+
+    fn has_valid_neighbor(&self, idx: usize) -> bool {
+        !self.find_valid_moves(idx).is_empty()
+    }
+}
+
+impl fmt::Debug for Grid<Cell> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for r in 0usize..self.num_rows() {
+            let range = self.row_first_idx(r)..=self.row_last_idx(r);
+            let line: String = self.vec[range]
+                .iter()
+                .map(|n| (n.get_height() + b'a') as char)
+                .collect();
+
+            writeln!(f, "{}", line)?;
+        }
+
+        Ok(())
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+#[derive(Debug)]
+pub struct Pathfinder {
+    start_idx: usize,
+    end_idx: usize,
+    grid: Grid<Cell>,
+    tree: Node,
+}
+
+impl Pathfinder {
+    pub fn from_file_str(file_str: &str) -> Self {
+        let mut pf = Pathfinder {
+            start_idx: 0,
+            end_idx: 0,
+            grid: Grid::from_file_str(file_str),
+            tree: Node::default(),
+        };
+
+        let start = pf.grid.find_pos(CellType::Start).unwrap();
+        let end = pf.grid.find_pos(CellType::End).unwrap();
+
+        pf.start_idx = start;
+        pf.end_idx = end;
+        pf.tree.idx = start;
+
+        pf
+    }
+
+    fn add_children(&mut self, node: &mut Node, idx: usize) {
+        let possible_moves = self.grid.find_valid_moves(idx);
+
+        if possible_moves.is_empty() {
+            return;
+        }
+
+        for m in possible_moves {
+            if node.contains(m) {
+                continue;
+            }
+
+            let n = node.add_child(m);
+            if m != self.end_idx {
+                self.add_children(n, m);
+            } else {
+                break;
+            }
+        }
+    }
+
+    fn build_tree(&mut self) {
+        let mut tree = { self.tree.clone() };
+        let idx = { self.start_idx };
+
+        self.add_children(&mut tree, idx);
+        self.tree = tree;
+    }
+
+    fn get_paths(&self) -> impl Iterator<Item = &Node> {
+        self.tree
+            .get_leaves()
+            .into_iter()
+            .filter(|n| n.idx == self.end_idx)
+    }
+
+    pub fn find_shortest_path(&mut self) -> &Node {
+        self.build_tree();
+
+        self.get_paths()
+            .min_by(|a, b| a.get_len().cmp(&b.get_len()))
+            .unwrap()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn get_test_data() -> &'static str {
+        include_str!("test-input.txt")
+    }
+
+    fn get_finder() -> Pathfinder {
+        Pathfinder::from_file_str(get_test_data())
+    }
+
+    #[test]
+    fn find_valid_moves() {
+        let finder = get_finder();
+
+        assert_eq!(finder.grid.find_valid_moves(finder.start_idx), vec![8, 1]);
+        assert_eq!(finder.grid.find_valid_moves(8), vec![0, 16, 9]);
+    }
+
+    #[test]
+    fn find_shortest_path() {
+        let mut finder = get_finder();
+        let shortest = finder.find_shortest_path();
+        assert_eq!(shortest.get_len(), 31);
+    }
+}
diff --git a/day12/src/main.rs b/day12/src/main.rs
index 7ba79af..6093f55 100644
--- a/day12/src/main.rs
+++ b/day12/src/main.rs
@@ -1,281 +1,7 @@
-mod node;
-use node::Node;
-
-use aoc_shared::enums::Direction;
-use aoc_shared::grid::Grid as BaseGrid;
-use aoc_shared::impl_grid_newtype;
-
-#[derive(Debug, Copy, Clone, PartialEq)]
-enum CellType {
-    Start,
-    End,
-    Waypoint(u8),
-}
-
-#[derive(Debug, Clone)]
-struct Cell {
-    kind: CellType,
-    idx: usize,
-    coord: (usize, usize),
-}
-
-impl Cell {
-    pub fn new(kind: CellType, idx: usize, coord: (usize, usize)) -> Self {
-        Cell { kind, idx, coord }
-    }
-
-    pub fn get_height(&self) -> u8 {
-        match self.kind {
-            CellType::Start => 0,
-            CellType::End => 25,
-            CellType::Waypoint(c) => c,
-        }
-    }
-}
-
-// ----------------------------------------------------------------------------
-
-#[derive(Debug)]
-pub struct Grid<T>(BaseGrid<T>);
-impl_grid_newtype!(Grid, BaseGrid<Cell>, Cell);
-
-impl Grid<Cell> {
-    pub fn from_file_str(file_str: &str) -> Self {
-        let first_line = file_str.lines().next().unwrap();
-        let width = first_line.len();
-
-        let mut grid = Grid::new(width);
-        let mut idx = 0usize;
-
-        for c in file_str.chars() {
-            let kind = match c {
-                'S' => CellType::Start,
-                'E' => CellType::End,
-                'a'..='z' => CellType::Waypoint(c as u8 - b'a'),
-                '\r' | '\n' => continue,
-                _ => panic!("Invalid character: {c}"),
-            };
-
-            let (x, y) = (idx % width, idx / width);
-            let cell = Cell::new(kind, idx, (x, y));
-
-            grid.vec.push(cell);
-
-            idx += 1;
-        }
-
-        grid
-    }
-
-    fn find_pos(&self, value: CellType) -> Option<usize> {
-        self.vec.iter().position(|item| item.kind == value)
-    }
-
-    pub fn print(&self) {
-        for r in 0usize..self.num_rows() {
-            let range = self.row_first_idx(r)..=self.row_last_idx(r);
-            let line: String = self.vec[range]
-                .iter()
-                .map(|n| (n.get_height() + b'a') as char)
-                .collect();
-
-            println!("{}", line);
-        }
-    }
-
-    fn get_index_for_move(&self, from: usize, dir: Direction) -> Option<usize> {
-        let (mut x, mut y) = self.idx_xy(from);
-
-        match dir {
-            Direction::Up => {
-                if y >= 1 {
-                    y -= 1;
-                } else {
-                    return None;
-                }
-            }
-            Direction::Down => {
-                if y < self.num_rows() - 1 {
-                    y += 1;
-                } else {
-                    return None;
-                }
-            }
-            Direction::Left => {
-                if x >= 1 {
-                    x -= 1;
-                } else {
-                    return None;
-                }
-            }
-            Direction::Right => {
-                if x < self.num_cols() - 1 {
-                    x += 1;
-                } else {
-                    return None;
-                }
-            }
-        };
-
-        Some(self.xy_idx(x, y))
-    }
-
-    fn is_valid_move(&self, start: usize, end: usize) -> bool {
-        // Is the item within the grid?
-        let start_char = self.get(start);
-        let end_char = self.get(end);
-        if start_char.is_none() || end_char.is_none() {
-            return false;
-        }
-
-        let start_char = start_char.unwrap();
-        let end_char = end_char.unwrap();
-        let start_elevation = start_char.get_height();
-        let end_elevation = end_char.get_height();
-        if (end_elevation < start_elevation) || end_elevation.abs_diff(start_elevation) > 1 {
-            return false;
-        }
-
-        let ((start_x, start_y), (end_x, end_y)) = (start_char.coord, end_char.coord);
-        let x_diff = end_x.abs_diff(start_x);
-        let y_diff = end_y.abs_diff(start_y);
-
-        // Have we moved 0 or 1 in a cardinal direction?
-        matches!((x_diff, y_diff), (0, 0) | (0, 1) | (1, 0))
-    }
-
-    fn find_moves(&self, start: usize) -> Vec<usize> {
-        [
-            Direction::Up,
-            Direction::Down,
-            Direction::Left,
-            Direction::Right,
-        ]
-        .into_iter()
-        .filter_map(|d| self.get_index_for_move(start, d))
-        .collect()
-    }
-
-    fn find_valid_moves(&self, start: usize) -> Vec<usize> {
-        self.find_moves(start)
-            .into_iter()
-            .filter(|m| self.is_valid_move(start, *m))
-            .collect()
-    }
-
-    fn has_valid_neighbor(&self, idx: usize) -> bool {
-        !self.find_valid_moves(idx).is_empty()
-    }
-}
-
-// ----------------------------------------------------------------------------
-
-#[derive(Debug)]
-pub struct Pathfinder {
-    start_idx: usize,
-    end_idx: usize,
-    grid: Grid<Cell>,
-    tree: Node,
-}
-
-impl Pathfinder {
-    pub fn from_file_str(file_str: &str) -> Self {
-        let mut pf = Pathfinder {
-            start_idx: 0,
-            end_idx: 0,
-            grid: Grid::from_file_str(file_str),
-            tree: Node::default(),
-        };
-
-        let start = pf.grid.find_pos(CellType::Start).unwrap();
-        let end = pf.grid.find_pos(CellType::End).unwrap();
-
-        pf.start_idx = start;
-        pf.end_idx = end;
-        pf.tree.idx = start;
-
-        pf
-    }
-
-    fn add_children(&mut self, node: &mut Node, idx: usize) {
-        let possible_moves = self.grid.find_valid_moves(idx);
-
-        if possible_moves.is_empty() {
-            return;
-        }
-
-        for m in possible_moves {
-            if node.contains(m) {
-                continue;
-            }
-
-            let n = node.add_child(m);
-            if m != self.end_idx {
-                self.add_children(n, m);
-            } else {
-                break;
-            }
-        }
-    }
-
-    fn build_tree(&mut self) {
-        let mut tree = { self.tree.clone() };
-        let idx = { self.start_idx };
-
-        self.add_children(&mut tree, idx);
-        self.tree = tree;
-    }
-
-    fn get_paths(&self) -> impl Iterator<Item = &Node> {
-        self.tree
-            .get_leaves()
-            .into_iter()
-            .filter(|n| n.idx == self.end_idx)
-    }
-
-    pub fn find_shortest_path(&mut self) -> &Node {
-        self.build_tree();
-
-        self.get_paths()
-            .min_by(|a, b| a.get_len().cmp(&b.get_len()))
-            .unwrap()
-    }
-}
-
-// ----------------------------------------------------------------------------
-
 fn main() {
     let file_str = include_str!("input.txt");
-    let mut finder = Pathfinder::from_file_str(file_str);
+    let mut finder = ::day12::Pathfinder::from_file_str(file_str);
     let shortest_path = finder.find_shortest_path();
 
     println!("Part 1: Fewest steps: {}", shortest_path.get_len());
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    fn get_test_data() -> &'static str {
-        include_str!("test-input.txt")
-    }
-
-    fn get_finder() -> Pathfinder {
-        Pathfinder::from_file_str(get_test_data())
-    }
-
-    #[test]
-    fn find_valid_moves() {
-        let finder = get_finder();
-
-        assert_eq!(finder.grid.find_valid_moves(finder.start_idx), vec![8, 1]);
-        assert_eq!(finder.grid.find_valid_moves(8), vec![0, 16, 9]);
-    }
-
-    #[test]
-    fn find_shortest_path() {
-        let mut finder = get_finder();
-        let shortest = finder.find_shortest_path();
-        assert_eq!(shortest.get_len(), 31);
-    }
-}
diff --git a/day12/src/node.rs b/day12/src/node.rs
index faae32a..32cabce 100644
--- a/day12/src/node.rs
+++ b/day12/src/node.rs
@@ -20,9 +20,7 @@ impl Node {
 
         self.append(child);
 
-        self.children
-            .last_mut()
-            .unwrap()
+        self.children.last_mut().unwrap()
     }
 
     fn append(&mut self, node: Node) -> &mut Self {
@@ -50,9 +48,7 @@ impl Node {
 
         let mut leaves = Vec::new();
 
-        let children = self
-            .children
-            .iter();
+        let children = self.children.iter();
 
         for child in children {
             let mut child_leaves = child.get_leaves();
@@ -65,4 +61,4 @@ impl Node {
     pub fn get_len(&self) -> usize {
         self.parents.len()
     }
-}
\ No newline at end of file
+}