linked-lists

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
+end

01-data-structures/03-linked-lists/node.rb

@@ -3,5 +3,6 @@ class Node
   attr_accessor :data
 
   def initialize(data)
+    @data = data
   end
-end
+end