Erica

lib/queue.rb

@@ -1,31 +1,55 @@
+QUEUE_SIZE = 20
+
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = Array.new(QUEUE_SIZE)
+    @front = @rear = -1
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1 #Q is empty
+      @rear = 1
+      @front = 0
+      @store[@front] = element
+    elsif @front == @rear
+      raise ArgumentError, "Queue is full"
+    else
+      new_rear = (@rear + 1) % QUEUE_SIZE
+      @store[@rear] = element
+      @rear = new_rear
+    end
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1 
+      raise ArgumentError, "Queue is empty"
+    else
+      dequeued = @store[@front]
+      @store[@front] = nil
+      @front = (@front + 1) % QUEUE_SIZE
+      return dequeued
+    end
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    return @store[@front]
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    return @store.compact.length
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    queue = @store.compact
+    if queue.length == 0
+      return true
+    else
+      return false
+    end
   end
 
   def to_s
-    return @store.to_s
+    return @store.compact.to_s
   end
 end

lib/stack.rb

@@ -1,22 +1,46 @@
 class Stack
+  STACK_SIZE = 20
+
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = Array.new(QUEUE_SIZE)
+    @front = @rear = -1
   end
 
   def push(element)
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1
+      @rear = 1
+      @front = 0
+      @store[@front] = element
+    elsif @front == @rear
+      raise ArgumentError, "Stack is full"
+    else
+      new_rear = (@rear + 1) % STACK_SIZE
+      @store[@rear] = element
+      @rear = new_rear
+    end
   end
 
   def pop
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1 
+      raise ArgumentError, "Stack is empty"
+    else
+      popped = @store[@rear - 1]
+      @store[@rear - 1] = nil
+      @rear = (@rear - 1) % STACK_SIZE
+      return popped
+    end
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    stack = @store.compact
+    if stack.length == 0
+      return true
+    else
+      return false
+    end
   end
 
   def to_s
-    return @store.to_s
+    return @store.compact.to_s
   end
 end

test/queue_test.rb

@@ -11,14 +11,12 @@
   end
 
   it "adds something to an empty Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
     q.to_s.must_equal "[10]"
   end
 
   it "adds multiple somethings to a Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
     q.enqueue(20)
@@ -27,13 +25,11 @@
   end
 
   it "starts the size of a Queue at 0" do
-    skip
     q = Queue.new
     q.empty?.must_equal true
   end
 
   it "removes something from the Queue" do
-    skip
     q = Queue.new
     q.enqueue(5)
     removed = q.dequeue
@@ -42,7 +38,6 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
     q = Queue.new
     q.enqueue(5)
     q.enqueue(3)
@@ -53,7 +48,6 @@
   end
 
   it "properly adjusts the size with enqueueing and dequeueing" do
-    skip
     q = Queue.new
     q.empty?.must_equal true
     q.enqueue(-1)
@@ -65,7 +59,6 @@
   end
 
   it "returns the front element in the Queue" do
-    skip
     q = Queue.new
     q.enqueue(40)
     q.enqueue(22)

test/stack_test.rb

@@ -10,14 +10,12 @@
   end
 
   it "pushes something onto a empty Stack" do
-    skip
     s = Stack.new
     s.push(10)
     s.to_s.must_equal "[10]"
   end
 
   it "pushes multiple somethings onto a Stack" do
-    skip
     s = Stack.new
     s.push(10)
     s.push(20)
@@ -26,13 +24,11 @@
   end
 
   it "starts the stack empty" do
-    skip
     s = Stack.new
     s.empty?.must_equal true
   end
 
   it "removes something from the stack" do
-    skip
     s = Stack.new
     s.push(5)
     removed = s.pop
@@ -41,7 +37,6 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
     s = Stack.new
     s.push(5)
     s.push(3)