From 420a95dff62e3fc798dbd97ea0bb89e6a62075d0 Mon Sep 17 00:00:00 2001
From: nahome <nahom.teshome@yahoo.com>
Date: Sun, 10 Jun 2018 18:24:47 -0700
Subject: [PATCH] linked-lists

---
 .../03-linked-lists/linked_list.rb            | 43 ++++++++++++++++++-
 01-data-structures/03-linked-lists/node.rb    |  3 +-
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/01-data-structures/03-linked-lists/linked_list.rb b/01-data-structures/03-linked-lists/linked_list.rb
index 5ee2a533..9db66678 100644
--- a/01-data-structures/03-linked-lists/linked_list.rb
+++ b/01-data-structures/03-linked-lists/linked_list.rb
@@ -6,25 +6,66 @@ class LinkedList
 
   # This method creates a new `Node` using `data`, and inserts it at the end of the list.
   def add_to_tail(node)
+    if @head = nil
+      self.head = node
+      self.tail = node
+    else
+      self.tail.next = node
+      self.node  = node
+    end
   end
 
   # This method removes the last node in the lists and must keep the rest of the list intact.
   def remove_tail
+    current = @head
+    while current.next.next != nil
+      current = current.next
+    end
+    @tail = current
+    @tail.next = nil
   end
 
   # This method prints out a representation of the list.
   def print
+    current = self.head
+    puts current.data
+    until current = self.tail
+      current = current.next
+      puts current.data
+    end
   end
 
   # This method removes `node` from the list and must keep the rest of the list intact.
   def delete(node)
+    if self.head == node
+      remove_front
+    elsif self.tail == node
+      remove_tail
+    else
+      current_node = self.head
+      until current_node.next == node
+        current_node = current_node.next
+      end
+      current_node.next = node.next
+    end
   end
 
   # This method adds `node` to the front of the list and must set the list's head to `node`.
   def add_to_front(node)
+    unless self.head.nil?
+      node.next = self.head
+    else
+      self.head = node
+    end
   end
 
   # This method removes and returns the first node in the Linked List and must set Linked List's head to the second node.
   def remove_front
+    unless self.head.next.nil?
+      self.head = self.head.next
+    else
+      self.head = nil
+      self.tail = nil
+    end
   end
-end
\ No newline at end of file
+end
diff --git a/01-data-structures/03-linked-lists/node.rb b/01-data-structures/03-linked-lists/node.rb
index 016acb90..4358f9f2 100644
--- a/01-data-structures/03-linked-lists/node.rb
+++ b/01-data-structures/03-linked-lists/node.rb
@@ -3,5 +3,6 @@ class Node
   attr_accessor :data
 
   def initialize(data)
+    @data = data
   end
-end
\ No newline at end of file
+end