diff --git a/Cargo.lock b/Cargo.lock
index 2523ece..4f33286 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "addr2line"
@@ -21,6 +21,7 @@ checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
 name = "advent_of_code"
 version = "0.11.0"
 dependencies = [
+ "bisection",
  "chrono",
  "dhat",
  "itertools",
@@ -74,6 +75,12 @@ dependencies = [
  "rustc-demangle",
 ]
 
+[[package]]
+name = "bisection"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "021e079a1bab0ecce6cf4b4b74c0c37afa4a697136eb3b127875c84a8f04a8c3"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
diff --git a/Cargo.toml b/Cargo.toml
index 9616f41..6b8378c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -30,3 +30,4 @@ tinyjson = "2.5.1"
 # Solution dependencies
 regex = "1.11.1"
 itertools = "0.13.0"
+bisection = "0.1.0"
diff --git a/data/examples/07.txt b/data/examples/07.txt
new file mode 100644
index 0000000..09a921e
--- /dev/null
+++ b/data/examples/07.txt
@@ -0,0 +1,23 @@
+$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k
diff --git a/src/bin/07.rs b/src/bin/07.rs
new file mode 100644
index 0000000..b50298d
--- /dev/null
+++ b/src/bin/07.rs
@@ -0,0 +1,152 @@
+use bisection::bisect_left;
+use std::{cell::RefCell, collections::HashMap, rc::Rc};
+
+advent_of_code::solution!(7);
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let fs = parse_input(input);
+
+    let mut ans = 0;
+    let dir_sizes = fs.get_dir_sizes();
+
+    for size in dir_sizes {
+        if size <= 100000 {
+            ans += size;
+        }
+    }
+
+    Some(ans)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let fs = parse_input(input);
+
+    let mut dir_sizes = fs.get_dir_sizes();
+    dir_sizes.sort();
+
+    let needed_size = dir_sizes.last().unwrap() - 40000000;
+    let i = bisect_left(&dir_sizes, &needed_size);
+
+    Some(dir_sizes[i])
+}
+
+struct Dir {
+    id: String,
+    parent: Option<Rc<RefCell<Dir>>>,
+    dirs: HashMap<String, Rc<RefCell<Dir>>>,
+    files: HashMap<String, u32>,
+}
+
+impl Dir {
+    fn new(id: String, parent: Option<Rc<RefCell<Dir>>>) -> Self {
+        Self {
+            id,
+            parent,
+            dirs: HashMap::new(),
+            files: HashMap::new(),
+        }
+    }
+}
+
+struct FileSystem {
+    root: Rc<RefCell<Dir>>,
+    cd: Rc<RefCell<Dir>>,
+}
+
+impl FileSystem {
+    fn new() -> Self {
+        let root = Rc::new(RefCell::new(Dir::new("/".to_string(), None)));
+        let cd = root.clone();
+        Self { root, cd }
+    }
+
+    fn cd(&mut self, dir_id: String) {
+        if dir_id == "/" {
+            self.cd = self.root.clone();
+        } else if dir_id == ".." {
+            let parent = self.cd.borrow().parent.clone();
+
+            if let Some(parent) = parent {
+                self.cd = parent;
+            }
+        } else {
+            let new_dir = self
+                .cd
+                .borrow_mut()
+                .dirs
+                .entry(dir_id.clone())
+                .or_insert_with(|| {
+                    Rc::new(RefCell::new(Dir::new(
+                        dir_id.clone(),
+                        Some(self.cd.clone()),
+                    )))
+                })
+                .clone();
+
+            self.cd = new_dir;
+        }
+    }
+
+    fn add_file(&self, file: (&str, &str)) {
+        self.cd
+            .borrow_mut()
+            .files
+            .insert(file.1.to_string(), file.0.parse::<u32>().unwrap());
+    }
+
+    fn get_dir_sizes(&self) -> Vec<u32> {
+        fn dfs(dir: Rc<RefCell<Dir>>, _dir_sizes: &mut Vec<u32>) -> u32 {
+            let dir = dir.borrow();
+
+            let mut size = dir.files.values().sum();
+            for child in dir.dirs.values() {
+                size += dfs(child.clone(), _dir_sizes);
+            }
+            _dir_sizes.push(size);
+
+            size
+        }
+
+        let mut dir_sizes = vec![];
+
+        dfs(self.root.clone(), &mut dir_sizes);
+
+        dir_sizes
+    }
+}
+
+fn parse_input(input: &str) -> FileSystem {
+    let mut fs = FileSystem::new();
+
+    input.lines().for_each(|line| match line {
+        line if line.starts_with("$ cd") => {
+            let id = line.trim_start_matches("$ cd ");
+            fs.cd(id.to_string());
+        }
+        line if line.starts_with("$ ls") => {}
+        line if line.starts_with("dir") => {}
+        _ => {
+            let file = line.split_once(" ").unwrap();
+            fs.add_file(file);
+        }
+    });
+
+    fs
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(95437));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(24933642));
+    }
+}