Branches - Erika

lib/linked_list.rb

@@ -10,36 +10,75 @@ 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
+    curr = @head
+    count = 0
+    until curr == nil
+      count += 1
+      curr = curr.next
+    end
+    return count
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def add_last(data)
-
+    curr = @head
+    if @head == nil
+      @head = Node.new(data)
+    else
+      until curr.next == nil
+        curr = curr.next
+      end
+      curr.next = Node.new(data)
+    end
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_last
-
+    curr = @head
+    if @head == nil
+      return nil
+    else
+      until curr.next == nil
+        curr = curr.next
+      end
+      return curr.data
+    end
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_at_index(index)
-
+    count = 0
+    curr = @head
+    if @head == nil
+      return nil
+    elsif index == 0
+      return @head.data
+    else
+      until count == index || curr.next == nil
+        curr = curr.next
+        count += 1
+      end
+    end
+    return curr.data
   end
+
 end

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
@@ -66,12 +66,18 @@
     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
     end
 
+    it "will return nil if the list is empty" do
+      expect(@list.get_last).must_be_nil
+    end
+
+
     it "will put new items to the rear of the list" do
       @list.add_last(2)
       expect(@list.length).must_equal 1
@@ -91,7 +97,7 @@
 
   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