From 98c29bdca0b43642f511d3818307a57a8871ca0d Mon Sep 17 00:00:00 2001
From: Kelsey Krippaehne <kelseykripp@gmail.com>
Date: Sun, 8 Dec 2019 12:45:52 -0800
Subject: [PATCH 1/2] Added working methods

---
 lib/linked_list.rb       | 56 +++++++++++++++++++++++++++++++++++-----
 test/linked_list_test.rb |  8 +++---
 2 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 9e97557..c54fc33 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -10,36 +10,80 @@ def initialize
   # Time complexity - ?
   # Space complexity - ?
   def add_first(data)
-
+    node = Node.new(data, @head)
+    @head = node
+    return @head.data
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_first
-
+    return @head.data if @head
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def length
-    return 0
+    count = 0
+    if @head
+      next_node = @head.next
+      count += 1
+      while next_node != nil
+        count += 1
+        next_node = next_node.next
+      end
+    end
+    return count
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def add_last(data)
-
+    if @head
+      if @head.next
+        next_node = @head.next
+        until next_node.next == nil
+          next_node = next_node.next
+        end
+        next_node.next = Node.new(data)
+      else
+        @head.next = Node.new(data)
+      end
+    else
+      @head = Node.new(data)
+    end
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_last
-
+    if @head.next
+      last_node = @head.next
+      while last_node.next != nil
+        last_node = last_node.next
+      end
+      return last_node.data
+    elsif @head
+      return @head.data
+    else
+      return nil
+    end
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_at_index(index)
-
+    if @head.nil? 
+      return nil
+    else
+      index = index
+      node_index = 0
+      next_node = @head
+      until node_index == index || next_node == nil
+        node_index += 1
+        next_node = next_node.next
+      end
+      return next_node.data
+    end
   end
 end
diff --git a/test/linked_list_test.rb b/test/linked_list_test.rb
index 2a805c7..fac4c41 100644
--- a/test/linked_list_test.rb
+++ b/test/linked_list_test.rb
@@ -21,7 +21,7 @@
     end
   end
 
-  xdescribe 'add_first & get_first' do
+  describe 'add_first & get_first' do
     it 'can add values to an empty list' do
       # Act
         @list.add_first(3)
@@ -51,7 +51,7 @@
     end
   end
 
-  xdescribe "length" do
+  describe "length" do
     it "will return 0 for an empty list" do
       expect(@list.length).must_equal 0
     end
@@ -66,7 +66,7 @@
     end
   end
 
-  xdescribe "addLast & getLast" do
+  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
@@ -91,7 +91,7 @@
 
   end
 
-  xdescribe 'get_at_index' do
+  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

From 3387bd12588d9f7342da3412b841e9a7cfe1d7b1 Mon Sep 17 00:00:00 2001
From: Kelsey Krippaehne <kelseykripp@gmail.com>
Date: Mon, 9 Dec 2019 14:46:29 -0800
Subject: [PATCH 2/2] Added time & space complexity

---
 lib/linked_list.rb | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index c54fc33..4ecedee 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -7,22 +7,22 @@ def initialize
     @head = nil
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(1)
+  # Space complexity - O(1), thanks to the power of linked lists we are not making any new data structures, just one new node.
   def add_first(data)
     node = Node.new(data, @head)
     @head = node
     return @head.data
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(1)
+  # Space complexity - O(1)
   def get_first
     return @head.data if @head
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n), where n is the length of the list
+  # Space complexity - O(1)
   def length
     count = 0
     if @head
@@ -36,8 +36,8 @@ def length
     return count
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n)
+  # Space complexity - O(1)
   def add_last(data)
     if @head
       if @head.next
@@ -54,8 +54,8 @@ def add_last(data)
     end
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n)
+  # Space complexity - O(1)
   def get_last
     if @head.next
       last_node = @head.next
@@ -70,8 +70,8 @@ def get_last
     end
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n), where `n` = index
+  # Space complexity - O(1)
   def get_at_index(index)
     if @head.nil? 
       return nil