diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 8dee5e8d..034624dc 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -3,7 +3,7 @@
 class Node
   attr_reader :data # allow external entities to read value but not write
   attr_accessor :next # allow external entities to read or write next node
-
+  
   def initialize(value, next_node = nil)
     @data = value
     @next = next_node
@@ -12,120 +12,197 @@ 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
-
-    # 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
-    def add_first(value)
-      raise NotImplementedError
-    end
-
-    # method to find if the linked list contains a node with specified value
-    # returns true if found, false otherwise
-    def search(value)
-      raise NotImplementedError
-    end
-
-    # method to return the max value in the linked list
-    # returns the data value and not the node
-    def find_max
-      raise NotImplementedError
-    end
-
-    # method to return the min value in the linked list
-    # returns the data value and not the node
-    def find_min
-      raise NotImplementedError
-    end
-
-
-    # method that returns the length of the singly linked list
-    def length
-      raise NotImplementedError
-    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
-    def get_at_index(index)
-      raise NotImplementedError
-    end
-
-    # method to print all the values in the linked list
-    def visit
-      raise NotImplementedError
-    end
-
-    # method to delete the first node found with specified value
-    def delete(value)
-      raise NotImplementedError
-    end
-
-    # method to reverse the singly linked list
-    # note: the nodes should be moved and not just the values in the nodes
-    def reverse
-      raise NotImplementedError
-    end
-
-
-    ## Advanced Exercises
-    # returns the value at the middle element in the singly linked list
-    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
-    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.
-    def has_cycle
-      raise NotImplementedError
-    end
-
-
-    # Additional Exercises 
-    # returns the value in the first node
-    # returns nil if the list is empty
-    def get_first
-      raise NotImplementedError
-    end
-
-    # method that inserts a given value as a new last node in the linked list
-    def add_last(value)
-      raise NotImplementedError
-    end
-
-    # method that returns the value of the last node in the linked list
-    # returns nil if the linked list is empty
-    def get_last
-      raise NotImplementedError
+  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
+  def add_first(value)
+    @head = Node.new(value, @head)
+  end
+  
+  # method to find if the linked list contains a node with specified value
+  # returns true if found, false otherwise
+  def search(value)
+    return false if @head.nil?
+    curr = @head
+    until curr.next.nil?
+      return true if curr.data == value
+      curr = curr.next
+    end
+    return curr.data == value
+  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?
+    max = @head.data
+    curr = @head.next
+    until curr.nil?
+      max = curr.data if max < curr.data
+      curr = curr.next
+    end
+    return max
+  end
+  
+  # method to return the min value in the linked list
+  # returns the data value and not the node
+  def find_min
+    return nil if @head.nil?
+    min = @head.data
+    curr = @head.next
+    until curr.nil?
+      min = curr.data if min > curr.data
+      curr = curr.next
+    end
+    return min
+  end
+  
+  
+  # method that returns the length of the singly linked list
+  def length
+    count = 0
+    return count if @head.nil?
+    curr = @head
+    until curr.nil?
+      count += 1
+      curr = curr.next
+    end
+    return count
+  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
+  def get_at_index(index)
+    return nil if index < 0 || index >= self.length
+    curr = @head
+    index.times do 
+      curr = curr.next
+    end
+    return curr.data
+  end
+  
+  # method to print all the values in the linked list
+  def visit
+    return nil if @head.nil?
+    curr = @head
+    until curr.nil?
+      p curr.data
+      curr = curr.next
     end
-
-    # method to insert a new node with specific data value, assuming the linked
-    # list is sorted in ascending order
-    def insert_ascending(value)
-      raise NotImplementedError
+  end
+  
+  # method to delete the first node found with specified value
+  def delete(value)
+    return nil if @head.nil?
+    if value == @head.data
+      @head = @head.next
+    else
+      prev = @head
+      curr = @head.next
+      until curr.data == value || curr.next.nil?
+        prev = curr
+        curr = curr.next
+      end
+      if curr.data == value 
+        prev.next = curr.next
+      end
     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
+  
+  # method to reverse the singly linked list
+  # note: the nodes should be moved and not just the values in the nodes
+  def reverse
+    return nil if @head.nil?
+    curr = @head 
+    prev = nil 
+    until curr.nil?
+      temp = curr.next
+      curr.next = prev
+      prev = curr 
+      curr = temp
+    end
+    @head = prev
+  end
+  
+  ## Advanced Exercises
+  # returns the value at the middle element in the singly linked list
+  def find_middle_value
+    return nil if @head.nil?
+    return self.get_at_index(self.length/2)
+  end
+  
+  # find the nth node from the end and return its value
+  # assume indexing starts at 0 while counting to n
+  def find_nth_from_end(n)
+    return nil if @head.nil? || n > self.length - 1
+    curr = @head
+    res = @head
+    n.times do 
+      curr = curr.next
+    end
+    until curr.next.nil?
+      curr = curr.next
+      res = res.next
+    end
+    return res.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.
+  def has_cycle
+    raise NotImplementedError
+  end
+  
+  # Additional Exercises 
+  # returns the value in the first node
+  # returns nil if the list is empty
+  def get_first
+    return @head.nil? ? nil : @head.data
+  end
+  
+  # method that inserts a given value as a new last node in the linked list
+  def add_last(value)
+    if @head.nil?
+      self.add_first(value)
+    else
+      curr = @head
+      until curr.next.nil?
+        curr = curr.next
       end
-
-      current.next = @head # make the last node link to first node
+      curr.next = Node.new(value)
     end
+  end
+  
+  # method that returns the value of the last node in the linked list
+  # returns nil if the linked list is empty
+  def get_last
+    return nil if @head.nil?
+    self.get_at_index(self.length - 1)
+  end
+  
+  # method to insert a new node with specific data value, assuming the linked
+  # list is sorted in ascending order
+  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
+    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 d169c9a0..bac48b55 100644
--- a/test/linked_list_test.rb
+++ b/test/linked_list_test.rb
@@ -8,221 +8,221 @@
 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
-
-    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_first).must_equal 3
     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_first).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_first).must_equal 2
-
-            # Act again
-            @list.add_first(3)
-
-            # Assert
-            expect(@list.get_first).must_equal 3
-        end
-
-        it 'will return `nil` for `getFirst` if the list is empty' do
-
-            expect(@list.get_first).must_be_nil
-        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_first).must_equal 2
+      
+      # Act again
+      @list.add_first(3)
+      
+      # Assert
+      expect(@list.get_first).must_equal 3
     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
+    
+    it 'will return `nil` for `getFirst` if the list is empty' do
+      
+      expect(@list.get_first).must_be_nil
     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 "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
-
-    describe "addLast & getLast" do
-        it "will add to the front if the list is empty" do
-            @list.add_last(1)
-            expect(@list.get_first).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_first).must_equal 2
-            expect(@list.get_last).must_equal 3
-            expect(@list.length).must_equal 2
-
-            @list.add_last(4)
-            expect(@list.get_first).must_equal 2
-            expect(@list.get_last).must_equal 4
-            expect(@list.length).must_equal 3
-        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
-
-    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
+    
+    it "returns false for an empty list" do
+      expect(@list.search(3)).must_equal false
     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_last(100)
-            @list.add_first(-12)
-            expect(@list.find_max).must_equal 100
-            expect(@list.find_min).must_equal(-12)
-        end
+  end
+  
+  describe "length" do
+    it "will return 0 for an empty list" do
+      expect(@list.length).must_equal 0
     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_last(9)
-            @list.add_last(10)
-            @list.add_first(4)
-            @list.add_first(3)
-            @list.add_first(2)
-
-            # delete fist node (requires updating head)
-            @list.delete(2)
-            expect(@list.get_first).must_equal 3
-            expect(@list.length).must_equal 4
-            expect(@list.get_last).must_equal 10
-            expect(@list.find_max).must_equal 10
-            expect(@list.find_min).must_equal 3
-
-            # delete last node
-            @list.delete(10)
-            expect(@list.get_first).must_equal 3
-            expect(@list.length).must_equal 3
-            expect(@list.get_last).must_equal 9
-            expect(@list.find_max).must_equal 9
-            expect(@list.find_min).must_equal 3
-
-            # delete fist node (requires updating head)
-            @list.delete(4)
-            expect(@list.get_first).must_equal 3
-            expect(@list.length).must_equal 2
-            expect(@list.get_last).must_equal 9
-            expect(@list.find_max).must_equal 9
-            expect(@list.find_min).must_equal 3
-        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
-
-    describe "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 "addLast & getLast" do
+    it "will add to the front if the list is empty" do
+      @list.add_last(1)
+      expect(@list.get_first).must_equal 1
     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.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
-        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_first).must_equal 2
+      expect(@list.get_last).must_equal 3
+      expect(@list.length).must_equal 2
+      
+      @list.add_last(4)
+      expect(@list.get_first).must_equal 2
+      expect(@list.get_last).must_equal 4
+      expect(@list.length).must_equal 3
+    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 '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_last(100)
+      @list.add_first(-12)
+      expect(@list.find_max).must_equal 100
+      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_last(9)
+      @list.add_last(10)
+      @list.add_first(4)
+      @list.add_first(3)
+      @list.add_first(2)
+      
+      # delete fist node (requires updating head)
+      @list.delete(2)
+      expect(@list.get_first).must_equal 3
+      expect(@list.length).must_equal 4
+      expect(@list.get_last).must_equal 10
+      expect(@list.find_max).must_equal 10
+      expect(@list.find_min).must_equal 3
+      
+      # delete last node
+      @list.delete(10)
+      expect(@list.get_first).must_equal 3
+      expect(@list.length).must_equal 3
+      expect(@list.get_last).must_equal 9
+      expect(@list.find_max).must_equal 9
+      expect(@list.find_min).must_equal 3
+      
+      # delete fist node (requires updating head)
+      @list.delete(4)
+      expect(@list.get_first).must_equal 3
+      expect(@list.length).must_equal 2
+      expect(@list.get_last).must_equal 9
+      expect(@list.find_max).must_equal 9
+      expect(@list.find_min).must_equal 3
+    end
+  end
+  
+  describe "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.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
     end
+  end
 end