Jillian - Finished methods for linked lists.

array-list.rb

@@ -2,27 +2,62 @@
 
 class ArrayList
   def initialize
-    @storage = []
+    #This array has the capacity of five. When we tell Ruby Array.new (or we just throw up some brackets) Ruby goes and reserves space in memory for our Array. That is what we are trying to illustrate.
+    # storage = capacity (what _could_ it hold)
+    @storage = [nil, nil, nil, nil, nil]
+    @size = 0
   end
 
   def add(value)
+    #We are putting the value in the index that is equal to the size of the array. If the size is 0, the value goes into the zero index position.
+    @storage[@size] = value
+    @size += 1
   end
 
   def delete(value)
+    return nil if empty?
+    @size -= 1
+
+    #We could do this, but we don't need to. @storage will always have 5 spots in it, we can just adjust the @size to reflect what we want to be in the array. We COULD delete the very last value, but don't NEED to.
+    # @storage[@size] = nil
   end
 
   def display
+    #Linearly we are printing each value within storage.
+    @size.times do |i|
+      puts @storage[i]
+    end
   end
 
   def include?(key)
+    @size.times do |i|
+      if @storage[i] = key
+        return true
+      end
+    end
+    #This false is not, and should not be a part of the above if loop as an else. If it _were_ the loop would stop once it met the first not "key" value in the array.
+    return false
   end
 
   def size
+    return @size
   end
 
   def max
+    # We start by assuming that the biggest value is 0. As we go through the array we check to see if each value is bigger that 0. If the value being passed through the loop is greater, then the value of biggest is replaced by the value.
+    return nil if empty?
+    biggest = 0
+    @size.times do |i|
+      if @storage[i] > @storage[biggest]
+        biggest = i
+      end
+    end
+    return @storage[biggest]
   end
 
+  def empty?
+    @size == 0
+  end
 end
 
 # Initializing an Array List
@@ -37,5 +72,5 @@ def max
 arr.display
 
 puts "Delete 10 and then display the array list:"
-arr.delete(10)
+arr.delete
 arr.display

linked-list.rb

@@ -3,74 +3,102 @@
 # LinkedList -> This class holds the linked list functions - adding a node, traversing and displaying the linked list
 
 class Node
-   attr_accessor :value, :next_node
+ attr_accessor :value, :next_node
 
-   def initialize(val,next_in_line=null)
-       @value = val
-       @next_nodex = next_in_line
-       puts "Initialized a Node with value:  " + value.to_s
-   end
+ def initialize(val,next_in_line=nil)
+   @value = val
+   @next_node = next_in_line
+   puts "Initialized a Node with value:  " + val.to_s
+ end
 end
 
 class LinkedList
-   def initialize(val)
-       # Initialize a new node at the head
-       @head = Node.new(val,nil)
-   end
-
-   def add(value)
-       # Traverse to the end of the list
-       # And insert a new node over there with the specified value
-       current = @head
-       while current.next_node != nil
-           current = current.next_node
-       end
-       current.next_node = Node.new(value,nil)
-       self
-   end
-
-   def delete(val)
-       current = @head
-       if current.value == val
-           # If the head is the element to be delete, the head needs to be updated
-           @head = @head.next_node
-       else
-           # ... x -> y -> z
-           # Suppose y is the value to be deleted, you need to reshape the above list to :
-           #   ... x->z
-           # ( and z is basically y.next_node )
-           current = @head
-           while (current != nil) && (current.next_node != nil) && ((current.next_node).value != val)
-               current = current.next_node
-           end
-
-           if (current != nil) && (current.next_node != nil)
-               current.next_node = (current.next_node).next_node
-           end
-       end
+#In a LinkedList each node only knows what the node in front of it is, it does not know what the node behind it was, or what the last node is. It only knows about the next node.
+ def initialize(val)
+  # Initialize a new node at the head
+  @head = Node.new(val,nil)
+ end
+
+ def add(value)
+  # Traverse to the end of the list
+  # And insert a new node over there with the specified value
+  current = @head
+  while current.next_node != nil
+    current = current.next_node
+  end
+  current.next_node = Node.new(value,nil)
+  self
+ end
+
+ def delete(val)
+  current = @head
+  if current.value == val
+    # If the head is the element to be delete, the head needs to be updated
+    @head = @head.next_node
+  else
+    # ... x -> y -> z
+    # Suppose y is the value to be deleted, you need to reshape the above list to :
+    #   ... x->z
+    # ( and z is basically y.next_node )
+    current = @head
+      while (current != nil) && (current.next_node != nil) && ((current.next_node).value != val)
+        current = current.next_node
+      end
+
+      if (current != nil) && (current.next_node != nil)
+        current.next_node = (current.next_node).next_node
+      end
+    end
+  end
+
+ def display
+  # Traverse through the list till you hit the "nil" at the end
+  current = @head
+  full_list = []
+  while current.next_node != nil
+    full_list += [current.value.to_s]
+    current = current.next_node
+  end
+  full_list += [current.value.to_s]
+  puts full_list.join("->")
+ end
+
+ def include?(key)
+   current = @head
+   while current != nil
+     if current.value != key
+       current = current.next_node
+     elsif current.value == key
+       puts "true"
+       return true
+     else
+       puts "false"
+       return false
+     end
    end
-
-   def display
-       # Traverse through the list till you hit the "nil" at the end
-       current = @head
-       full_list = []
-       while current.next_node != nil
-           full_list += [current.value.to_s]
-           current = current.next_node
-       end
-       full_list += [current.value.to_s]
-       puts full_list.join("->")
+ end
+
+ def size
+   count = 1
+   current = @head
+   while current.next_node != nil
+     count += 1
+     current = current.next_node
    end
-
-   def include?(key)
+   return count
+ end
+
+ def max
+   max = 0
+   current = @head
+   while current != nil
+     if current.value > max
+       max = current.value
+     end
+     current = current.next_node
    end
-
-   def size
-   end
-
-   def max
-   end
-
+   return max
+ end
 end
 
 # Initializing a Linked List with a node containing value (5)
@@ -88,6 +116,16 @@ def max
 ll.delete(10)
 ll.display
 
+# Find element in list:
+puts "Is 20 in the list?"
+"#{ll.include?(20)}"
+
+# Give the size of the list:
+puts "The size of the list is #{ll.size}."
+
+#Find the highest value in the list:
+puts "The highest value in the list is #{ll.max}."
+
 =begin
 Output:
 Initialized a Node with value:  5
@@ -97,4 +135,8 @@ def max
 5->10->20
 Delete 10 and then display the linked list:
 5->20
+Is 20 in the list?
+true
+The size of the list is 2.
+The highest value in the list is 20.
 =end