diff --git a/src/assignments/assignment11/graph.rs b/src/assignments/assignment11/graph.rs
index 77b8586..e8d1c0d 100644
--- a/src/assignments/assignment11/graph.rs
+++ b/src/assignments/assignment11/graph.rs
@@ -16,6 +16,8 @@ use std::cell::RefCell;
 use std::collections::HashSet;
 use std::rc::Rc;
 
+use itertools::Itertools;
+
 #[derive(PartialEq, Eq, Debug)]
 enum VisitStatus {
     Unvisited,
@@ -23,6 +25,12 @@ enum VisitStatus {
     Visited,
 }
 
+#[derive(Debug)]
+struct Node {
+    value: i32,
+    next: Vec<Rc<RefCell<Node>>>,
+}
+
 /// Handle to a graph node.
 ///
 /// `NodeHandle` should implement `Clone`, which clones the handle without cloning the underlying
@@ -31,7 +39,9 @@ enum VisitStatus {
 ///
 /// You can freely add fields to this struct.
 #[derive(Debug, Clone)]
-pub struct NodeHandle;
+pub struct NodeHandle {
+    node: Rc<RefCell<Node>>,
+}
 
 /// Error type for graph operations.
 #[derive(Debug)]
@@ -41,12 +51,19 @@ pub struct GraphError;
 ///
 /// You can freely add fields to this struct.
 #[derive(Debug)]
-pub struct SubGraph;
+pub struct SubGraph {
+    nodes: Vec<Rc<RefCell<Node>>>,
+}
 
 impl NodeHandle {
     /// Creates a node and returns the handle to it.
     pub fn new(value: i32) -> Self {
-        todo!()
+        NodeHandle {
+            node: Rc::new(RefCell::new(Node {
+                value,
+                next: vec![],
+            })),
+        }
     }
 
     /// Adds an edge to `to`.
@@ -54,7 +71,16 @@ impl NodeHandle {
     /// `Err(GraphError)`. Returns `Ok(true)` if the edge is successfully added.
     /// Returns `Ok(false)` if an edge to `to` already exits.
     pub fn add_edge(&self, to: NodeHandle) -> Result<bool, GraphError> {
-        todo!()
+        let mut my_node = match self.node.try_borrow_mut() {
+            Ok(r) => r,
+            Err(_) => return Err(GraphError),
+        };
+        if my_node.next.iter().any(|v| Rc::ptr_eq(v, &to.node)) {
+            Ok(false)
+        } else {
+            my_node.next.push(to.node.clone());
+            Ok(true)
+        }
     }
 
     /// Removes the edge to `to`.
@@ -62,14 +88,32 @@ impl NodeHandle {
     /// `Err(GraphError)`. Returns `Ok(true)` if the edge is successfully removed.
     /// Returns `Ok(false)` if an edge to `to` does not exist.
     pub fn remove_edge(&self, to: &NodeHandle) -> Result<bool, GraphError> {
-        todo!()
+        let mut my_node = match self.node.try_borrow_mut() {
+            Ok(r) => r,
+            Err(_) => return Err(GraphError),
+        };
+        let index = my_node
+            .next
+            .iter()
+            .find_position(|v| Rc::ptr_eq(v, &to.node));
+        if let Some((index, _)) = index {
+            let _unused = my_node.next.remove(index);
+            Ok(true)
+        } else {
+            Ok(false)
+        }
     }
 
     /// Removes all edges.
     /// If the modification cannot be done, e.g. because of aliasing issues, returns
     /// `Err(GraphError)`.
     pub fn clear_edges(&self) -> Result<(), GraphError> {
-        todo!()
+        let mut my_node = match self.node.try_borrow_mut() {
+            Ok(r) => r,
+            Err(_) => return Err(GraphError),
+        };
+        my_node.next.clear();
+        Ok(())
     }
 }
 
@@ -82,22 +126,65 @@ impl Default for SubGraph {
 impl SubGraph {
     /// Creates a new subgraph.
     pub fn new() -> Self {
-        todo!()
+        SubGraph { nodes: vec![] }
     }
 
     /// Adds a node to the subgraph. Returns true iff the node is newly added.
     pub fn add_node(&mut self, node: NodeHandle) -> bool {
-        todo!()
+        let index = self
+            .nodes
+            .iter()
+            .find_position(|v| Rc::ptr_eq(v, &node.node));
+        if index.is_none() {
+            self.nodes.push(node.node.clone());
+            true
+        } else {
+            false
+        }
     }
 
     /// Removes a node from the subgraph. Returns true iff the node is successfully removed.
     pub fn remove_node(&mut self, node: &NodeHandle) -> bool {
-        todo!()
+        let index = self
+            .nodes
+            .iter()
+            .find_position(|v| Rc::ptr_eq(v, &node.node));
+        if let Some((index, _)) = index {
+            let _unused = self.nodes.remove(index);
+            true
+        } else {
+            false
+        }
     }
 
     /// Returns true iff the subgraph contains a cycle. Nodes that do not belong to this subgraph
     /// are ignored. See <https://en.wikipedia.org/wiki/Cycle_(graph_theory)> for an algorithm.
     pub fn detect_cycle(&self) -> bool {
-        todo!()
+        fn helper(subgraph: &SubGraph, visited: &mut HashSet<usize>, node: usize) -> bool {
+            if visited.contains(&node) {
+                return true;
+            }
+
+            let _ = visited.insert(node);
+
+            for next in &subgraph.nodes[node].borrow().next {
+                let next_index = subgraph.nodes.iter().find_position(|n| Rc::ptr_eq(n, next));
+                if let Some((next_index, _)) = next_index {
+                    let mut visited = visited.clone();
+                    if helper(subgraph, &mut visited, next_index) {
+                        return true;
+                    }
+                }
+            }
+            false
+        }
+
+        for i in 0..self.nodes.len() {
+            let mut visited = HashSet::new();
+            if helper(self, &mut visited, i) {
+                return true;
+            }
+        }
+        false
     }
 }
diff --git a/src/assignments/assignment11/linked_list.rs b/src/assignments/assignment11/linked_list.rs
index 8cb7718..4e5acca 100644
--- a/src/assignments/assignment11/linked_list.rs
+++ b/src/assignments/assignment11/linked_list.rs
@@ -42,37 +42,87 @@ impl<T: Debug> SinglyLinkedList<T> {
 
     /// Adds the given node to the front of the list.
     pub fn push_front(&mut self, value: T) {
-        todo!()
+        let next = self.head.take().map(Box::new);
+        self.head = Some(Node { value, next })
     }
 
     /// Adds the given node to the back of the list.
     pub fn push_back(&mut self, value: T) {
-        todo!()
+        let new_node = Node { value, next: None };
+        if let Some(ref mut head) = self.head {
+            let mut current = head;
+            while let Some(ref mut next) = current.next {
+                current = next;
+            }
+            current.next = Some(Box::new(new_node));
+        } else {
+            self.head = Some(new_node);
+        }
     }
 
     /// Removes and returns the node at the front of the list.
     pub fn pop_front(&mut self) -> Option<T> {
-        todo!()
+        if let Some(head) = self.head.take() {
+            self.head = head.next.map(|n| *n);
+            Some(head.value)
+        } else {
+            None
+        }
     }
 
     /// Removes and returns the node at the back of the list.
     pub fn pop_back(&mut self) -> Option<T> {
-        todo!()
+        if let Some(head) = &mut self.head {
+            if head.next.is_none() {
+                return Some(self.head.take().unwrap().value);
+            }
+
+            let mut prev = head;
+            while let Some(next) = &mut prev.next.as_mut().unwrap().next {
+                prev = prev.next.as_mut().unwrap();
+            }
+
+            Some(prev.next.take().unwrap().value)
+        } else {
+            None
+        }
     }
 
     /// Create a new list from the given vector `vec`.
     pub fn from_vec(vec: Vec<T>) -> Self {
-        todo!()
+        let mut result = Self::new();
+
+        for e in vec {
+            result.push_back(e);
+        }
+
+        result
     }
 
     /// Convert the current list into a vector.
     pub fn into_vec(self) -> Vec<T> {
-        todo!()
+        let mut result = vec![];
+        let mut current = self.head;
+
+        while let Some(node) = current {
+            result.push(node.value);
+            current = node.next.map(|n| *n);
+        }
+
+        result
     }
 
     /// Return the length (i.e., number of nodes) of the list.
     pub fn length(&self) -> usize {
-        todo!()
+        let mut result = 0;
+        let mut current = self.head.as_ref();
+
+        while let Some(node) = current {
+            result += 1;
+            current = node.next.as_deref();
+        }
+
+        result
     }
 
     /// Apply function `f` on every element of the list.
@@ -81,7 +131,15 @@ impl<T: Debug> SinglyLinkedList<T> {
     ///
     /// `self`: `[1, 2]`, `f`: `|x| x + 1` ==> `[2, 3]`
     pub fn map<F: Fn(T) -> T>(self, f: F) -> Self {
-        todo!()
+        let mut result = Self::new();
+        let mut current = self.head;
+
+        while let Some(node) = current {
+            result.push_back(f(node.value));
+            current = node.next.map(|n| *n);
+        }
+
+        result
     }
 
     /// Apply given function `f` for each adjacent pair of elements in the list.
@@ -97,7 +155,23 @@ impl<T: Debug> SinglyLinkedList<T> {
     where
         T: Clone,
     {
-        todo!()
+        if self.length() < 2 {
+            return self;
+        }
+
+        let mut result = SinglyLinkedList::new();
+        let (mut prev, mut current) = {
+            let head = self.head.unwrap();
+            (head.value, head.next)
+        };
+
+        while let Some(node) = current {
+            result.push_back(f(prev, node.value.clone()));
+            prev = node.value;
+            current = node.next;
+        }
+
+        result
     }
 }
 
@@ -109,6 +183,19 @@ impl<T: Debug> SinglyLinkedList<SinglyLinkedList<T>> {
     /// `self`: `[[1, 2, 3], [4, 5, 6], [7, 8]]`
     /// ==> `[1, 2, 3, 4, 5, 6, 7, 8]`
     pub fn flatten(self) -> SinglyLinkedList<T> {
-        todo!()
+        let mut result = SinglyLinkedList::new();
+        let mut current = self.head;
+
+        while let Some(node) = current {
+            let mut inner_current = node.value.head;
+            while let Some(node) = inner_current {
+                result.push_back(node.value);
+                inner_current = node.next.map(|n| *n);
+            }
+
+            current = node.next.map(|n| *n);
+        }
+
+        result
     }
 }
diff --git a/src/assignments/assignment11/mock_storage.rs b/src/assignments/assignment11/mock_storage.rs
index 4e0edc2..657c875 100644
--- a/src/assignments/assignment11/mock_storage.rs
+++ b/src/assignments/assignment11/mock_storage.rs
@@ -47,15 +47,30 @@ pub trait Storage {
 
 impl Storage for MockStorage {
     fn upload(&self, name: &str, size: usize) -> Result<(), usize> {
-        todo!()
+        let used = self.used();
+        let mut files = self.files.borrow_mut();
+        let old_size = files.get(name).unwrap_or(&0);
+
+        if used - old_size + size <= self.capacity() {
+            let _ = files.insert(String::from(name), size);
+            Ok(())
+        } else {
+            Err(size - (self.capacity - (used - old_size)))
+        }
     }
 
     fn used(&self) -> usize {
-        todo!()
+        let mut result = 0;
+
+        for size in self.files.borrow().values() {
+            result += size;
+        }
+
+        result
     }
 
     fn capacity(&self) -> usize {
-        todo!()
+        self.capacity
     }
 }
 
@@ -75,7 +90,7 @@ impl<'a, T: Storage> FileUploader<'a, T> {
 
     /// Uploads a file to the internal storage.
     pub fn upload(&self, name: &str, size: usize) -> Result<(), usize> {
-        todo!()
+        self.storage.upload(name, size)
     }
 }
 
@@ -94,6 +109,6 @@ impl<'a, T: Storage> UsageAnalyzer<'a, T> {
 
     /// Returns `true` if the usage of the internal storage is under the bound.
     pub fn is_usage_under_bound(&self) -> bool {
-        todo!()
+        (self.storage.used() as f64) / (self.storage.capacity() as f64) <= self.bound
     }
 }
diff --git a/src/assignments/assignment11/tv_room.rs b/src/assignments/assignment11/tv_room.rs
index d1ae8b6..1101858 100644
--- a/src/assignments/assignment11/tv_room.rs
+++ b/src/assignments/assignment11/tv_room.rs
@@ -56,12 +56,20 @@ impl TVRoom {
     ///
     /// Returns `None` if the TV room is already opened.
     pub fn open(&self) -> Option<Manager<'_>> {
-        todo!()
+        if self.is_opened() {
+            None
+        } else {
+            *self.state.borrow_mut() = TVRoomState::Opened;
+            Some(Manager::new(&self.state))
+        }
     }
 
     /// Returns whether the TV room is opened or not.
     pub fn is_opened(&self) -> bool {
-        todo!()
+        match *self.state.borrow() {
+            TVRoomState::Opened => true,
+            TVRoomState::Closed => false,
+        }
     }
 }
 
@@ -84,7 +92,9 @@ impl<'a> Manager<'a> {
 
     /// Adds new guest to the TV room.
     pub fn new_guest(&self) -> Guest<'a> {
-        todo!()
+        Guest {
+            inner: self.inner.clone(),
+        }
     }
 }
 
@@ -108,6 +118,6 @@ impl<'a> Watcher<'a> {
 impl Drop for Watcher<'_> {
     fn drop(&mut self) {
         // When the last person leaves the TV room, the TV room should be closed.
-        todo!()
+        *self.tvstate.borrow_mut() = TVRoomState::Closed;
     }
 }