Water - Jessica

README.md

@@ -2,7 +2,7 @@
 
 In this exercise we will implement both a stack & a queue, and then use them in a variety of hands-on exercises.
 
-**Due:  Monday Sept 7th**
+**Due:  Tuesday Sept 8th**
 
 ## Learning Goals
 

lib/linked_list.rb

@@ -37,7 +37,7 @@ def remove_first()
 
       value = @head.data
       @head = @head.next
-      @head.previous = nil
+      @head.previous = nil unless @head.nil?
       return value
     end
 
@@ -339,4 +339,4 @@ def to_s
 
       return list.to_s
     end
-end
+end

lib/queue.rb

@@ -1,31 +1,63 @@
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @size = 20
+    @store = Array.new
+    @front = -1
+    @rear = -1
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    if (@front == 0 && @rear == @size - 1) || (@rear == (@front - 1) % (@size-1))
+      raise ArgumentError.new('Queue is full')
+    elsif @front == -1 && @rear == -1
+      @front = @rear = 0
+    elsif @rear == @size - 1 && @front != 0
+      @rear = 0
+    else
+      @rear = @rear + 1
+    end
+
+    @store[@rear] = element
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1
+      raise ArgumentError.new('Queue is empty')
+    end
+
+    data = @store[@front]
+    @store[@front] = nil
+
+    if @front == @rear
+      @front = @rear = -1
+    elsif @front == @size - 1
+      @front = 0
+    else
+      @front = @front + 1
+    end
+
+    return data
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    return @store[@front]
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    return @back >= @front ? (@back - @front) : (@size - @front + @back)
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @front == -1
   end
 
   def to_s
-    return @store.to_s
+    queue = []
+    @size.times do |i|
+      index = (i + @front) % @size
+      queue << @store[index] if @store[index]
+    end
+    return queue.to_s
   end
 end

lib/stack.rb

@@ -1,19 +1,20 @@
 class Stack
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new
   end
 
   def push(element)
-    raise NotImplementedError, "Not yet implemented"
+    @store.add_first(element)
   end
 
   def pop
-    raise NotImplementedError, "Not yet implemented"
+    return nil if self.empty?
+
+    return @store.remove_first()
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @store.empty?
   end
 
   def to_s

test/stack_test.rb

@@ -3,21 +3,23 @@
 describe "Test Stack Implementation" do
   it "creates a Stack" do
     s = Stack.new
-    s.class.must_equal Stack
+    expect(s.class).must_equal Stack
   end
 
   it "pushes something onto a empty Stack" do
     s = Stack.new
     s.push(10)
-    s.to_s.must_equal "[10]"
+    expect(s.pop).must_equal 10
   end
 
   it "pushes multiple somethings onto a Stack" do
     s = Stack.new
     s.push(10)
     s.push(20)
     s.push(30)
-    s.to_s.must_equal "[10, 20, 30]"
+    expect(s.pop).must_equal 30
+    expect(s.pop).must_equal 20
+    expect(s.pop).must_equal 10
   end
 
   it "starts the stack empty" do
@@ -29,8 +31,8 @@
     s = Stack.new
     s.push(5)
     removed = s.pop
-    removed.must_equal 5
-    s.empty?.must_equal true
+    expect(removed).must_equal 5
+    expect(s.empty?).must_equal true
   end
 
   it "removes the right something (LIFO)" do
@@ -39,7 +41,6 @@
     s.push(3)
     s.push(7)
     removed = s.pop
-    removed.must_equal 7
-    s.to_s.must_equal "[5, 3]"
+    expect(removed).must_equal 7
   end
-end
+end