From cfe01a59e5b2fbb4109cbf57cf41b8cf93595416 Mon Sep 17 00:00:00 2001
From: marks214 <aimee.oz.x@gmail.com>
Date: Fri, 11 Dec 2020 16:39:38 -0800
Subject: [PATCH 1/3] linked_list.rb is now working

---
 .idea/.gitignore         |  6 ++++++
 .idea/linked-lists.iml   | 27 +++++++++++++++++++++++++++
 .idea/misc.xml           |  4 ++++
 .idea/modules.xml        |  8 ++++++++
 .idea/vcs.xml            |  6 ++++++
 .rakeTasks               |  7 +++++++
 Gemfile.lock             | 36 ++++++++++++++++++++++++++++++++++++
 lib/linked_list.rb       | 34 ++++++++++++++++++++++++++++++----
 lib/node.rb              |  4 ++--
 test/linked_list_test.rb |  8 ++++----
 10 files changed, 130 insertions(+), 10 deletions(-)
 create mode 100644 .idea/.gitignore
 create mode 100644 .idea/linked-lists.iml
 create mode 100644 .idea/misc.xml
 create mode 100644 .idea/modules.xml
 create mode 100644 .idea/vcs.xml
 create mode 100644 .rakeTasks
 create mode 100644 Gemfile.lock

diff --git a/.idea/.gitignore b/.idea/.gitignore
new file mode 100644
index 0000000..8bf4d45
--- /dev/null
+++ b/.idea/.gitignore
@@ -0,0 +1,6 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml
diff --git a/.idea/linked-lists.iml b/.idea/linked-lists.iml
new file mode 100644
index 0000000..a1a27da
--- /dev/null
+++ b/.idea/linked-lists.iml
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="RUBY_MODULE" version="4">
+  <component name="ModuleRunConfigurationManager">
+    <shared />
+  </component>
+  <component name="NewModuleRootManager">
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/features" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/spec" isTestSource="true" />
+      <sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" scope="PROVIDED" name="ansi (v1.5.0, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="builder (v3.2.4, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="bundler (v2.1.4, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="coderay (v1.1.3, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="method_source (v1.0.0, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="minitest (v5.14.2, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="minitest-reporters (v1.4.2, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="minitest-skip (v0.0.3, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="minitest-spec (v0.0.2.1, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="pry (v0.13.1, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="rake (v13.0.1, rbenv: 2.6.5) [gem]" level="application" />
+    <orderEntry type="library" scope="PROVIDED" name="ruby-progressbar (v1.10.1, rbenv: 2.6.5) [gem]" level="application" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..510e7fc
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectRootManager" version="2" project-jdk-name="rbenv: 2.6.5" project-jdk-type="RUBY_SDK" />
+</project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
new file mode 100644
index 0000000..fae548e
--- /dev/null
+++ b/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/linked-lists.iml" filepath="$PROJECT_DIR$/.idea/linked-lists.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..94a25f7
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.rakeTasks b/.rakeTasks
new file mode 100644
index 0000000..e409da2
--- /dev/null
+++ b/.rakeTasks
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Settings><!--This file was automatically generated by Ruby plugin.
+You are allowed to: 
+1. Remove rake task
+2. Add existing rake tasks
+To add existing rake tasks automatically delete this file and reload the project.
+--><RakeGroup description="" fullCmd="" taksId="rake"><RakeTask description="Run tests" fullCmd="test" taksId="test" /><RakeTask description="" fullCmd="default" taksId="default" /></RakeGroup></Settings>
diff --git a/Gemfile.lock b/Gemfile.lock
new file mode 100644
index 0000000..630ea95
--- /dev/null
+++ b/Gemfile.lock
@@ -0,0 +1,36 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ansi (1.5.0)
+    builder (3.2.4)
+    coderay (1.1.3)
+    method_source (1.0.0)
+    minitest (5.14.2)
+    minitest-reporters (1.4.2)
+      ansi
+      builder
+      minitest (>= 5.0)
+      ruby-progressbar
+    minitest-skip (0.0.3)
+      minitest (~> 5.0)
+    minitest-spec (0.0.2.1)
+      minitest (>= 3.0)
+    pry (0.13.1)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    rake (13.0.1)
+    ruby-progressbar (1.10.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  minitest
+  minitest-reporters
+  minitest-skip
+  minitest-spec
+  pry
+  rake
+
+BUNDLED WITH
+   2.1.4
diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 9e97557..bd6a9ef 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -10,36 +10,62 @@ def initialize
   # Time complexity - ?
   # Space complexity - ?
   def add_first(data)
-
+    new_node = Node.new(data)
+    new_node.next = @head
+    @head = new_node
+    return @head
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_first
+    return @head.data unless @head.nil?
 
+    return nil
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def length
-    return 0
+    count = 0
+    current = @head
+    until current.nil?
+      count += 1
+      current = current.next
+    end
+
+    return count
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def add_last(data)
+    return add_first(data) if @head.nil?
+
+    current = @head
+    current = current.next until current.next.nil?
 
+    current.next = Node.new(data)
+    return current.next
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_last
-
+    return nil if @head.nil?
+    current = @head
+    current = current.next until current.next.nil?
+    return current.data
   end
 
   # Time complexity - ?
   # Space complexity - ?
   def get_at_index(index)
-
+    return nil if @head.nil?
+    current = @head
+    index.times do
+      current = current.next
+    end
+    return current.data
   end
 end
diff --git a/lib/node.rb b/lib/node.rb
index 469eca3..65a8e8c 100644
--- a/lib/node.rb
+++ b/lib/node.rb
@@ -3,8 +3,8 @@ class Node
   attr_reader :data
   attr_accessor :next
 
-  def initialize(value, nextNode = nil)
+  def initialize(value, next_node = nil)
     @data = value
-    @next = nextNode
+    @next = next_node
   end
 end
diff --git a/test/linked_list_test.rb b/test/linked_list_test.rb
index bdbbd06..8e558e7 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
@@ -93,7 +93,7 @@
     end
   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 5d8c5fac3acb53c69a0317945ed95a61459b9a73 Mon Sep 17 00:00:00 2001
From: marks214 <aimee.oz.x@gmail.com>
Date: Sat, 12 Dec 2020 17:09:19 -0800
Subject: [PATCH 2/3] added space and time complexities

---
 .idea/.rakeTasks   |  7 +++++++
 lib/linked_list.rb | 27 ++++++++++++++-------------
 2 files changed, 21 insertions(+), 13 deletions(-)
 create mode 100644 .idea/.rakeTasks

diff --git a/.idea/.rakeTasks b/.idea/.rakeTasks
new file mode 100644
index 0000000..e409da2
--- /dev/null
+++ b/.idea/.rakeTasks
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Settings><!--This file was automatically generated by Ruby plugin.
+You are allowed to: 
+1. Remove rake task
+2. Add existing rake tasks
+To add existing rake tasks automatically delete this file and reload the project.
+--><RakeGroup description="" fullCmd="" taksId="rake"><RakeTask description="Run tests" fullCmd="test" taksId="test" /><RakeTask description="" fullCmd="default" taksId="default" /></RakeGroup></Settings>
diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index bd6a9ef..35aac81 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -1,4 +1,6 @@
 require_relative 'node'
+# helpful resource I used to work on this:
+# https://hackernoon.com/implementing-singly-linked-list-with-ruby-om2df3ya6
 
 class LinkedList
   attr_reader :head
@@ -7,8 +9,8 @@ def initialize
     @head = nil
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(1)
+  # Space complexity - O(1)
   def add_first(data)
     new_node = Node.new(data)
     new_node.next = @head
@@ -16,16 +18,15 @@ def add_first(data)
     return @head
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(1)
+  # Space complexity - O(1)
   def get_first
     return @head.data unless @head.nil?
-
     return nil
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n)
+  # Space complexity - O(1)
   def length
     count = 0
     current = @head
@@ -37,8 +38,8 @@ def length
     return count
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n) - last element is unknown
+  # Space complexity - O(1)
   def add_last(data)
     return add_first(data) if @head.nil?
 
@@ -49,8 +50,8 @@ def add_last(data)
     return current.next
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n)
+  # Space complexity - O(1)
   def get_last
     return nil if @head.nil?
     current = @head
@@ -58,8 +59,8 @@ def get_last
     return current.data
   end
 
-  # Time complexity - ?
-  # Space complexity - ?
+  # Time complexity - O(n)
+  # Space complexity - O(1)
   def get_at_index(index)
     return nil if @head.nil?
     current = @head

From 4dd1873ce87054db2aa70fd87cf9a08b5dd52efd Mon Sep 17 00:00:00 2001
From: marks214 <aimee.oz.x@gmail.com>
Date: Mon, 14 Dec 2020 13:07:17 -0800
Subject: [PATCH 3/3] explained time complexities

---
 lib/linked_list.rb | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/linked_list.rb b/lib/linked_list.rb
index 35aac81..7f82bbf 100644
--- a/lib/linked_list.rb
+++ b/lib/linked_list.rb
@@ -9,7 +9,7 @@ def initialize
     @head = nil
   end
 
-  # Time complexity - O(1)
+  # Time complexity - O(1) - A node is added to the beginning of the list. Since this is not an array, we are not replacing an element and shifting the rest of the data over.
   # Space complexity - O(1)
   def add_first(data)
     new_node = Node.new(data)
@@ -18,14 +18,14 @@ def add_first(data)
     return @head
   end
 
-  # Time complexity - O(1)
+  # Time complexity - O(1) - We look up the first node (where the head is)
   # Space complexity - O(1)
   def get_first
     return @head.data unless @head.nil?
     return nil
   end
 
-  # Time complexity - O(n)
+  # Time complexity - O(n) we count n nodes in the list
   # Space complexity - O(1)
   def length
     count = 0
@@ -38,7 +38,7 @@ def length
     return count
   end
 
-  # Time complexity - O(n) - last element is unknown
+  # Time complexity - O(n) - need to traverse list of length n to find the last node and add one after that
   # Space complexity - O(1)
   def add_last(data)
     return add_first(data) if @head.nil?
@@ -50,7 +50,7 @@ def add_last(data)
     return current.next
   end
 
-  # Time complexity - O(n)
+  # Time complexity - O(n) - we need to traverse the list of length n to find the last node
   # Space complexity - O(1)
   def get_last
     return nil if @head.nil?
@@ -59,7 +59,7 @@ def get_last
     return current.data
   end
 
-  # Time complexity - O(n)
+  # Time complexity - O(n) - worst case scenario, we need to iterate through n times to find the node (not a direct look up)
   # Space complexity - O(1)
   def get_at_index(index)
     return nil if @head.nil?