diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 5e173ebc..6206500f 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -1,4 +1,3 @@
-
 # Defines a node in the singly linked list
 class Node
   attr_reader :data # allow external entities to read value but not write
@@ -12,148 +11,352 @@ def initialize(value, next_node = nil)
 
 # Defines the singly linked list
 class LinkedList
-    def initialize
-      @head = nil # keep the head private. Not accessible outside this class
-    end
+  def initialize
+    @head = nil # keep the head private. Not accessible outside this class
+  end
+
+  # method to add a new node with the specific data value in the linked list
+  # insert the new node at the beginning of the linked list
+  # Time Complexity: O(1)
+  # >> Constant num of actions - create new node,
+  # set next to old head, set head pointer to new node
+  # Space Complexity: O(1)
+  # >> Always adding 1 new node
+  def add_first(value)
+  @head = Node.new(value, @head)
+  end
 
-    # method to add a new node with the specific data value in the linked list
-    # insert the new node at the beginning of the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def add_first(value)
-      raise NotImplementedError
+  # method to find if the linked list contains a node with specified value
+  # returns true if found, false otherwise
+  # Time Complexity: O(n)
+  # >> Must check every single node in linked list
+  # Space Complexity: O(1)
+  # >> Just checking for membership; only ever store current_node
+  def search(value)
+    current_node = @head
+
+    until current_node.nil?
+      return true if current_node.data == value
+
+      current_node = current_node.next
     end
 
-    # method to find if the linked list contains a node with specified value
-    # returns true if found, false otherwise
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def search(value)
-      raise NotImplementedError
+    return false
+  end
+
+  # method to return the max value in the linked list
+  # returns the data value and not the node
+  def find_max
+    return nil if @head.nil?
+
+    current_node = @head
+    max = current_node.data
+
+    until current_node.nil?
+      max = current_node.data if current_node.data > max
+      current_node = current_node.next
     end
 
-    # method to return the max value in the linked list
-    # returns the data value and not the node
-    def find_max
-      raise NotImplementedError
+    return max
+  end
+
+  # method to return the min value in the linked list
+  # returns the data value and not the node
+  # Time Complexity: O(n)
+  # >> have to traverse entire linked list (unless we know it's sorted...)
+  # Space Complexity: O(1)
+  # >> store current_node and min regardless of how long LL is
+  def find_min
+    return nil if @head.nil?
+
+    current_node = @head
+    min = current_node.data
+
+    until current_node.nil?
+      min = current_node.data if current_node.data < min
+      current_node = current_node.next
     end
 
-    # method to return the min value in the linked list
-    # returns the data value and not the node
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def find_min
-      raise NotImplementedError
+    return min
+  end
+
+
+  # Additional Exercises
+  # returns the value in the first node
+  # returns nil if the list is empty
+  # Time Complexity: O(1)
+  # >> pointer to head
+  # Space Complexity: O(1)
+  # >> don't need to allocate space for vars - just returning value of first node if exists
+  def get_first
+    return nil if @head.nil?
+
+    return @head.data
+  end
+
+  # method that inserts a given value as a new last node in the linked list
+  # Time Complexity: O(n)
+  # >> Have to continue traversing linked list until reach last node (next is nil)
+  # >> Conversely, if we had a tail pointer, then this could be O(1) in a doubly-linked list
+  # Space Complexity: O(1)
+  # >> adding one new node each time (reference in next for an existing node, add new node)
+  def add_last(value)
+    if @head.nil?
+      @head = Node.new(value)
+      return
     end
 
+    current_node = @head
 
-    # Additional Exercises 
-    # returns the value in the first node
-    # returns nil if the list is empty
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def get_first
-      raise NotImplementedError
+    until current_node.next.nil?
+      current_node = current_node.next
     end
 
-    # method that inserts a given value as a new last node in the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def add_last(value)
-      raise NotImplementedError
+    current_node.next = Node.new(value)
+  end
+
+  # method that returns the length of the singly linked list
+  # Time Complexity: O(n)
+  # >> traverse length of ll to get num nodes in list
+  # Space Complexity: O(1)
+  # >> store len integer
+  def length
+    return 0 if @head.nil?
+
+    len = 1
+    current_node = @head.next
+
+    until current_node.nil?
+      len += 1
+      current_node = current_node.next
     end
 
-    # method that returns the length of the singly linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def length
-      raise NotImplementedError
+    return len
+  end
+
+  # method that returns the value at a given index in the linked list
+  # index count starts at 0
+  # returns nil if there are fewer nodes in the linked list than the index value
+  # Time Complexity: O(n)
+  # >> Traverse up to n nodes to get value at index position
+  # Space Complexity: O(1)
+  # >> store node_num and current_node
+  def get_at_index(index)
+    return nil if @head.nil?
+    return @head.data if index.zero?
+
+    node_num = 0
+    current_node = @head
+
+    until node_num == index || current_node.nil?
+      current_node = current_node.next
+      node_num += 1 unless current_node.nil?
     end
 
-    # method that returns the value at a given index in the linked list
-    # index count starts at 0
-    # returns nil if there are fewer nodes in the linked list than the index value
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def get_at_index(index)
-      raise NotImplementedError
+    return node_num == index ? current_node.data : nil
+  end
+
+  # method to print all the values in the linked list
+  # Time Complexity: O(n)
+  # >> Traverse entire LL to print all values
+  # Space Complexity: O(1)
+  # >> store current node
+  def visit
+    return nil if @head.nil?
+
+    current_node = @head
+
+    until current_node.nil?
+      p current_node.data
+      current_node = current_node.next
     end
+  end
+
+  # method to delete the first node found with specified value
+  # Time Complexity: O(n)
+  # >> search up to entire list to find node with specified value
+  # Space Complexity: O(1)
+  # >> keep track of current node
+  def delete(value)
+    return nil if @head.nil?
 
-    # method to print all the values in the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def visit
-      raise NotImplementedError
+    if @head.data == value
+      new_head = @head.next
+      @head.next = nil
+      @head = new_head
     end
 
-    # method to delete the first node found with specified value
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def delete(value)
-      raise NotImplementedError
+    current_node = @head
+    until current_node.next.nil?
+      if current_node.next.data == value
+        current_node.next = current_node.next.next
+        return
+      end
+      current_node = current_node.next
     end
 
-    # method to reverse the singly linked list
-    # note: the nodes should be moved and not just the values in the nodes
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def reverse
-      raise NotImplementedError
+    return nil
+  end
+
+  # method to reverse the singly linked list
+  # note: the nodes should be moved and not just the values in the nodes
+  # Time Complexity: O(n)
+  # >> traverse length of LL to reverse all nodes
+  # Space Complexity: O(1)
+  # >> store previous, current, and next nodes
+  def reverse
+    return nil if @head.nil?
+
+    current_node = @head
+    previous_node = nil
+    next_node = nil
+
+    while current_node
+      next_node = current_node.next
+      current_node.next = previous_node
+      previous_node = current_node
+      current_node = next_node
     end
 
-    # method that returns the value of the last node in the linked list
-    # returns nil if the linked list is empty
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def get_last
-      raise NotImplementedError
+    @head = previous_node
+  end
+
+  # method that returns the value of the last node in the linked list
+  # returns nil if the linked list is empty
+  # Time Complexity: O(n)
+  # >> traverse length of LL to get to last node
+  # Space Complexity: O(1)
+  # >> store current node
+  def get_last
+    return nil if @head.nil?
+
+    current_node = @head
+
+    until current_node.next.nil?
+      current_node = current_node.next
     end
+
+    return current_node.data
+  end
   
-    ## Advanced Exercises
-    # returns the value at the middle element in the singly linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def find_middle_value
-      raise NotImplementedError
-    end
-
-    # find the nth node from the end and return its value
-    # assume indexing starts at 0 while counting to n
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def find_nth_from_end(n)
-      raise NotImplementedError
-    end
-
-    # checks if the linked list has a cycle. A cycle exists if any node in the
-    # linked list links to a node already visited.
-    # returns true if a cycle is found, false otherwise.
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def has_cycle
-      raise NotImplementedError
-    end
-
-    # method to insert a new node with specific data value, assuming the linked
-    # list is sorted in ascending order
-    # Time Complexity: ?
-    # Space Complexity: ?
-    def insert_ascending(value)
-      raise NotImplementedError
-    end
-
-    # Helper method for tests
-    # Creates a cycle in the linked list for testing purposes
-    # Assumes the linked list has at least one node
-    def create_cycle
-      return if @head == nil # don't do anything if the linked list is empty
-
-      # navigate to last node
-      current = @head
-      while current.next != nil
-          current = current.next
+  ## Advanced Exercises
+  # returns the value at the middle element in the singly linked list
+  # Time Complexity: O(n)
+  # >> get length of LL (pass through all n nodes)
+  # >> go through half of those nodes
+  # Space Complexity: O(1)
+  # >> store mid_index, current_node, current_node_num
+  def find_middle_value
+    return nil if @head.nil?
+
+    mid_index = length / 2
+    current_node = @head
+    current_node_num = 0
+    
+    until current_node_num == mid_index
+      current_node = current_node.next
+      current_node_num += 1
+    end
+    
+    return current_node.data
+  end
+
+  # find the nth node from the end and return its value
+  # assume indexing starts at 0 while counting to n
+  # Time Complexity: O(n)
+  # >> pass through all nodes to get length
+  # >> at worst pass through all nodes again to get 0th node from end
+  # >> 2n --> n
+  # Space Complexity: O(1)
+  # >> store len, index, current_node, curr_node_num
+  def find_nth_from_end(n)
+    return nil if @head.nil?
+
+    len = length
+    return nil if n >= len # maybe better to throw ArgumentError here
+
+    index = len - n - 1
+    current_node = @head
+    curr_node_num = 0
+    until curr_node_num == index
+      current_node = current_node.next
+      curr_node_num += 1
+    end
+
+    return current_node.data
+  end
+
+  # checks if the linked list has a cycle. A cycle exists if any node in the
+  # linked list links to a node already visited.
+  # returns true if a cycle is found, false otherwise.
+  # Time Complexity: O(n)
+  # >> If no cycle, 'fast' and 'slow' pointers will go through LL once
+  # >> If cycle, 'slow' pointer will go through the list at most once
+  # >> b/c 'fast' cannot lap / overtake the 'slow' pointer if 'fast'
+  # >> moves two nodes at a time while 'slow' 1 node at a time
+  # >> if DID skip over --> slow --> fast
+  # >> previous step would mean both pointers were at the same node
+  # Space Complexity: O(1)
+  # >> fast and slow nodes
+  def has_cycle
+    return nil if @head.nil?
+
+    fast = slow = @head
+    while fast&.next
+      fast = fast.next.next
+      slow = slow.next
+
+      return true if slow == fast
+    end
+
+    return false
+  end
+
+  # method to insert a new node with specific data value, assuming the linked
+  # list is sorted in ascending order
+  # Time Complexity: O(n)
+  # >> worst case node has to be placed at end
+  # Space Complexity: O(1)
+  # >> store new_node and current_node
+  def insert_ascending(value)
+    new_node = Node.new(value)
+
+    return @head = new_node if @head.nil?
+
+    current_node = @head
+
+    if current_node.data > value
+      new_node.next = current_node
+      @head = new_node
+      return
+    end
+
+    while current_node.data <= value && current_node.next
+      if current_node.next.data > value
+        new_next_node = current_node.next
+        current_node.next = new_node
+        new_node.next = new_next_node
+        return
       end
 
-      current.next = @head # make the last node link to first node
+      current_node = current_node.next
     end
+
+    current_node.next = new_node
+  end
+
+  # Helper method for tests
+  # Creates a cycle in the linked list for testing purposes
+  # Assumes the linked list has at least one node
+  def create_cycle
+    return if @head.nil? # don't do anything if the linked list is empty
+
+    # navigate to last node
+    current = @head
+    while current.next != nil
+      current = current.next
+    end
+
+    current.next = @head # make the last node link to first node
+  end
 end
diff --git a/test/linked_list_test.rb b/test/linked_list_test.rb
index 77423e34..899dc363 100644
--- a/test/linked_list_test.rb
+++ b/test/linked_list_test.rb
@@ -1,245 +1,304 @@
 require_relative 'test_helper'
 
-
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 describe LinkedList do
-    # Arrange
-    before do
-        @list = LinkedList.new
+  # Arrange
+  before do
+    @list = LinkedList.new
+  end
+
+  describe 'initialize' do
+    it 'can be created' do
+      # Assert
+      expect(@list).must_be_kind_of LinkedList
+    end
+  end
+
+  describe 'add_first & get_first' do
+    it 'can add values to an empty list' do
+      # Act
+      @list.add_first(3)
+
+      # Assert
+      expect(@list.get_at_index(0)).must_equal 3
+    end
+
+    it 'will put the last added item to the front of the list' do
+      # Act
+      @list.add_first(1)
+      @list.add_first(2)
+
+      # Assert
+      expect(@list.get_at_index(0)).must_equal 2
+
+      # Act again
+      @list.add_first(3)
+
+      # Assert
+      expect(@list.get_at_index(0)).must_equal 3
+    end
+
+    it 'will return `nil` for `getFirst` if the list is empty' do
+      expect(@list.get_at_index(0)).must_be_nil
+    end
+  end
+
+  describe 'search' do
+    it 'can find an element' do
+      @list = LinkedList.new
+      @list.add_first(3)
+      @list.add_first(2)
+
+      expect(@list.search(3)).must_equal true
+
+      expect(@list.search(2)).must_equal true
+    end
+
+    it 'returns false if the element is not in the list' do
+      @list = LinkedList.new
+      @list.add_first(3)
+      @list.add_first(2)
+      expect(@list.search('pasta')).must_equal false
+    end
+
+    it 'returns false for an empty list' do
+      expect(@list.search(3)).must_equal false
+    end
+  end
+
+  describe 'length' do
+    it 'will return 0 for an empty list' do
+      expect(@list.length).must_equal 0
+    end
+
+    it 'will return the length for nonempty lists' do
+      count = 0
+      while count < 5
+        @list.add_first(count)
+        count += 1
+        expect(@list.length).must_equal count
+      end
+    end
+  end
+
+  describe 'get_at_index' do
+    it 'returns nil if the index is outside the bounds of the list' do
+      expect(@list.get_at_index(3)).must_be_nil
+    end
+
+    it 'can retrieve an item at an index in the list' do
+      @list.add_first(1)
+      @list.add_first(2)
+      @list.add_first(3)
+      @list.add_first(4)
+
+      expect(@list.get_at_index(0)).must_equal 4
+      expect(@list.get_at_index(1)).must_equal 3
+      expect(@list.get_at_index(2)).must_equal 2
+      expect(@list.get_at_index(3)).must_equal 1
+    end
+  end
+
+  describe 'Optional addLast & getLast' do
+    it 'will add to the front if the list is empty' do
+      @list.add_last(1)
+      expect(@list.get_at_index(0)).must_equal 1
     end
 
-    describe 'initialize' do
-        it 'can be created' do
+    it 'will put new items to the rear of the list' do
+      @list.add_last(2)
+      expect(@list.length).must_equal 1
+      expect(@list.get_last).must_equal 2
+
+      @list.add_last(3)
+      expect(@list.get_at_index(0)).must_equal 2
+      expect(@list.get_last).must_equal 3
+      expect(@list.length).must_equal 2
+
+      @list.add_last(4)
+      expect(@list.get_at_index(0)).must_equal 2
+      expect(@list.get_last).must_equal 4
+      expect(@list.length).must_equal 3
+    end
+  end
 
-            # Assert
-            expect(@list).must_be_kind_of LinkedList
-        end
+  describe 'max and min values' do
+    it 'returns nil if the list is empty' do
+      expect(@list.find_max()).must_be_nil
+      expect(@list.find_min()).must_be_nil
     end
 
-    describe 'add_first & get_first' do
-        it 'can add values to an empty list' do
-            # Act
-            @list.add_first(3)
+    it 'can retrieve the max and min values in the list' do
+      count = 0
+      while count < 5
+        @list.add_first(count)
+        expect(@list.find_max).must_equal count
+        expect(@list.find_min).must_equal 0
+        count += 1
+      end
+
+      @list.add_first(100)
+      @list.add_first(-12)
+      expect(@list.find_max).must_equal 100
+      expect(@list.find_min).must_equal(-12)
+      @list.add_last(99)
+      expect(@list.find_max).must_equal 100
+      @list.add_first(50)
+      expect(@list.find_min).must_equal(-12)
+    end
+  end
 
-            # Assert
-            expect(@list.get_at_index(0)).must_equal 3
-        end
+  describe 'delete' do
+    it 'delete from empty linked list is a no-op' do
+      expect(@list.length).must_equal 0
+      @list.delete(4)
+      expect(@list.length).must_equal 0
+    end
 
-        it 'will put the last added item to the front of the list' do
-            # Act
-            @list.add_first(1)
-            @list.add_first(2)
+    it 'can delete valid values from list' do
+      @list.add_first(9)
+      @list.add_first(10)
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+
+      # delete first node (requires updating head)
+      @list.delete(2)
+      expect(@list.get_first).must_equal 3
+      expect(@list.length).must_equal 4
+      expect(@list.get_at_index(@list.length - 1)).must_equal 9
+      expect(@list.find_max).must_equal 10
+      expect(@list.find_min).must_equal 3
+
+      # delete last node
+      @list.delete(10)
+      expect(@list.get_at_index(0)).must_equal 3
+      expect(@list.length).must_equal 3
+      expect(@list.get_at_index(@list.length - 1)).must_equal 9
+      expect(@list.find_max).must_equal 9
+      expect(@list.find_min).must_equal 3
+
+      # delete middle node (requires updating head)
+      @list.delete(4)
+      expect(@list.get_at_index(0)).must_equal 3
+      expect(@list.length).must_equal 2
+      expect(@list.get_at_index(@list.length - 1)).must_equal 9
+      expect(@list.find_max).must_equal 9
+      expect(@list.find_min).must_equal 3
+    end
 
-            # Assert
-            expect(@list.get_at_index(0)).must_equal 2
+    it 'can delete from the middle' do
+      # Arrange
+      @list.add_last(9)
+      @list.add_last(10)
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+
+      # Act
+      @list.delete(9)
+
+      # Assert
+      expect(@list.get_last).must_equal 10
+      expect(@list.length).must_equal 4
+      expect(@list.get_first).must_equal 2
+    end
+  end
 
-            # Act again
-            @list.add_first(3)
+  describe 'Optional: nth_from_the_end' do
+    it 'returns nil if n is outside the bounds of the list' do
+      expect(@list.find_nth_from_end(3)).must_be_nil
+    end
+
+    it 'can retrieve an item at index n from the end in the list' do
+      @list.add_first(1)
+      @list.add_first(2)
+      @list.add_first(3)
+      @list.add_first(4)
+
+      expect(@list.find_nth_from_end(0)).must_equal 1
+      expect(@list.find_nth_from_end(1)).must_equal 2
+      expect(@list.find_nth_from_end(2)).must_equal 3
+      expect(@list.find_nth_from_end(3)).must_equal 4
+      expect(@list.find_nth_from_end(4)).must_be_nil
+    end
+  end
+
+  describe 'reverse' do
+    it 'can retrieve an item at index n from the end in the list' do
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      @list.add_first(1)
+      @list.reverse
+
+      expect(@list.get_at_index(0)).must_equal 4
+      expect(@list.get_at_index(1)).must_equal 3
+      expect(@list.get_at_index(2)).must_equal 2
+      expect(@list.get_at_index(3)).must_equal 1
+    end
+  end
+
+  describe 'has_cycle' do
+    it 'correctly detects a cycle' do
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      @list.add_first(1)
+      @list.create_cycle
+
+      expect(@list.has_cycle).must_equal true
+    end
+
+    it 'correctly detects when there is not a cycle' do
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      @list.add_first(1)
+
+      expect(@list.has_cycle).must_equal false
+    end
+  end
+
+  describe 'insert_ascending' do
+    it 'can insert node at beginning of empty list' do
+      @list.insert_ascending(4)
+
+      expect(@list.get_at_index(0)).must_equal 4
+    end
+
+    it 'can insert node at beginning of list where all other nodes have higher values' do
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      @list.add_first(1)
+
+      @list.insert_ascending(0)
+
+      expect(@list.get_first).must_equal 0
+    end
+
+    it 'can insert node at end of list' do
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      @list.add_first(1)
+
+      @list.insert_ascending(5)
+
+      expect(@list.get_last).must_equal 5
+    end
 
-            # Assert
-            expect(@list.get_at_index(0)).must_equal 3
-        end
+    it 'can insert node in middle of list' do
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      @list.add_first(1)
 
-        it 'will return `nil` for `getFirst` if the list is empty' do
+      @list.insert_ascending(3)
 
-            expect(@list.get_at_index(0)).must_be_nil
-        end
-    end
-
-    describe "search" do
-        it "can find an element" do
-            @list = LinkedList.new
-            @list.add_first(3)
-            @list.add_first(2)
-
-            expect(@list.search(3)).must_equal true
-
-            expect(@list.search(2)).must_equal true
-        end
-
-        it "returns false if the element is not in the list" do
-          @list = LinkedList.new
-          @list.add_first(3)
-          @list.add_first(2)
-          expect(@list.search("pasta")).must_equal false
-        end
-
-        it "returns false for an empty list" do
-        expect(@list.search(3)).must_equal false
-        end
-    end
-
-    describe "length" do
-        it "will return 0 for an empty list" do
-            expect(@list.length).must_equal 0
-        end
-
-        it "will return the length for nonempty lists" do
-            count = 0
-            while count < 5
-                @list.add_first(count)
-                count += 1
-                expect(@list.length).must_equal count
-            end
-        end
-    end
-
-    describe 'get_at_index' do
-        it 'returns nil if the index is outside the bounds of the list' do
-            expect(@list.get_at_index(3)).must_be_nil
-        end
-
-        it 'can retrieve an item at an index in the list' do
-            @list.add_first(1)
-            @list.add_first(2)
-            @list.add_first(3)
-            @list.add_first(4)
-
-            expect(@list.get_at_index(0)).must_equal 4
-            expect(@list.get_at_index(1)).must_equal 3
-            expect(@list.get_at_index(2)).must_equal 2
-            expect(@list.get_at_index(3)).must_equal 1
-        end
-    end
-
-    xdescribe "Optional addLast & getLast" do
-        it "will add to the front if the list is empty" do
-            @list.add_last(1)
-            expect(@list.get_at_index(0)).must_equal 1
-        end
-
-        it "will put new items to the rear of the list" do
-            @list.add_last(2)
-            expect(@list.length).must_equal 1
-            expect(@list.get_last).must_equal 2
-
-            @list.add_last(3)
-            expect(@list.get_at_index(0)).must_equal 2
-            expect(@list.get_last).must_equal 3
-            expect(@list.length).must_equal 2
-
-            @list.add_last(4)
-            expect(@list.get_at_index(0)).must_equal 2
-            expect(@list.get_last).must_equal 4
-            expect(@list.length).must_equal 3
-        end
-    end
-
-    describe 'max and min values' do
-        it 'returns nil if the list is empty' do
-            expect(@list.find_max()).must_be_nil
-            expect(@list.find_min()).must_be_nil
-        end
-
-        it 'can retrieve the max and min values in the list' do
-            count = 0
-            while count < 5
-                @list.add_first(count)
-                expect(@list.find_max).must_equal count
-                expect(@list.find_min).must_equal 0
-                count += 1
-            end
-
-            @list.add_first(100)
-            @list.add_first(-12)
-            expect(@list.find_max).must_equal 100
-            expect(@list.find_min).must_equal(-12)
-            @list.add_last(99)
-            expect(@list.find_max).must_equal 100
-            @list.add_first(50)
-            expect(@list.find_min).must_equal(-12)
-        end
-    end
-
-    describe "delete" do
-        it "delete from empty linked list is a no-op" do
-            expect(@list.length).must_equal 0
-            @list.delete(4)
-            expect(@list.length).must_equal 0
-        end
-
-        it "can delete valid values from list" do
-            @list.add_first(9)
-            @list.add_first(10)
-            @list.add_first(4)
-            @list.add_first(3)
-            @list.add_first(2)
-
-            # delete first node (requires updating head)
-            @list.delete(2)
-            expect(@list.get_first).must_equal 3
-            expect(@list.length).must_equal 4
-            expect(@list.get_at_index(@list.length - 1)).must_equal 9
-            expect(@list.find_max).must_equal 10
-            expect(@list.find_min).must_equal 3
-
-            # delete last node
-            @list.delete(10)
-            expect(@list.get_at_index(0)).must_equal 3
-            expect(@list.length).must_equal 3
-            expect(@list.get_at_index(@list.length - 1)).must_equal 9
-            expect(@list.find_max).must_equal 9
-            expect(@list.find_min).must_equal 3
-
-            # delete middle node (requires updating head)
-            @list.delete(4)
-            expect(@list.get_at_index(0)).must_equal 3
-            expect(@list.length).must_equal 2
-            expect(@list.get_at_index(@list.length - 1)).must_equal 9
-            expect(@list.find_max).must_equal 9
-            expect(@list.find_min).must_equal 3
-        end
-
-        it "can delete from the middle" do
-            # Arrange
-            @list.add_last(9)
-            @list.add_last(10)
-            @list.add_first(4)
-            @list.add_first(3)
-            @list.add_first(2)
-
-            # Act
-            @list.delete(9)
-
-            # Assert
-            expect(@list.get_last).must_equal 10
-            expect(@list.length).must_equal 4
-            expect(@list.get_first).must_equal 2
-        end
-    end
-
-    xdescribe "Optional:  nth_from_the_end" do
-        it 'returns nil if n is outside the bounds of the list' do
-            expect(@list.find_nth_from_end(3)).must_be_nil
-        end
-
-        it 'can retrieve an item at index n from the end in the list' do
-            @list.add_first(1)
-            @list.add_first(2)
-            @list.add_first(3)
-            @list.add_first(4)
-
-            expect(@list.find_nth_from_end(0)).must_equal 1
-            expect(@list.find_nth_from_end(1)).must_equal 2
-            expect(@list.find_nth_from_end(2)).must_equal 3
-            expect(@list.find_nth_from_end(3)).must_equal 4
-            expect(@list.find_nth_from_end(4)).must_be_nil
-        end
-    end
-
-    describe "reverse" do
-        it 'can retrieve an item at index n from the end in the list' do
-            @list.add_first(4)
-            @list.add_first(3)
-            @list.add_first(2)
-            @list.add_first(1)
-            @list.reverse
-
-            expect(@list.get_at_index(0)).must_equal 4
-            expect(@list.get_at_index(1)).must_equal 3
-            expect(@list.get_at_index(2)).must_equal 2
-            expect(@list.get_at_index(3)).must_equal 1
-        end
+      expect(@list.get_at_index(3)).must_equal 3
     end
+  end
 end