From 1e865b5efad472b2223a2785f86c8c7f4379c1f4 Mon Sep 17 00:00:00 2001
From: Mariya Burrows <mariya.burrows@gmail.com>
Date: Mon, 9 Dec 2019 21:47:52 -0800
Subject: [PATCH] completed linked list hw exercises

---
 lib/linked_list.rb       | 42 ++++++++++++++++++++++++++++++++++++----
 test/linked_list_test.rb |  8 ++++----
 2 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 9e97557..0d65578 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -10,36 +10,70 @@ def initialize
   # Time complexity - ?
   # Space complexity - ?
   def add_first(data)
-
+    @head = Node.new(data, @head)
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_first
-
+    if @head.nil?
+        return nil
+    else 
+      return @head.data
+    end
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def length
-    return 0
+    count = 0
+    temp = @head 
+    while temp != nil 
+      count += 1
+      temp = temp.next
+    end 
+    return count
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def add_last(data)
+    new_node = Node.new(data)
 
+    if @head.nil? 
+      @head = new_node
+    else 
+      current = @head
+      until current.next.nil? 
+        current = current.next 
+      end
+      current.next = new_node
+    end
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_last
-
+    current = @head 
+    until current.next.nil? 
+      current = current.next
+    end 
+    return current.data
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_at_index(index)
+    current = @head 
+    if current.nil? 
+      return nil 
+    end
+
+    index.times do 
+      current = current.next
+    end
 
+    return current.data 
   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