Angela

lib/problems.rb

@@ -1,7 +1,25 @@
 require_relative './stack.rb'
 
 def balanced(string)
-  raise NotImplementedError, "Not implemented yet"
+  return false if string.length % 2 != 0
+  s_1 = Stack.new()
+  pairs = {
+    ")" => "(",
+    "}" => "{",
+    "]" => "["
+  }
+  string.each_char do |val|
+    if pairs.values.include?(val)
+      s_1.push(val)
+    else 
+      if pairs[val] == s_1.peak_last
+        s_1.pop
+      else
+        return false
+      end
+    end
+  end
+  return true if s_1.empty? 
 end
 
 def evaluate_postfix(postfix_expression)

lib/queue.rb

@@ -1,31 +1,60 @@
+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"
+  def enqueue(element) # add to rear
+    if @front == -1 # Queue is empty 
+      @rear = 1
+      @front = 0
+      @store[@front] = element
+    elsif @front == @rear
+      raise Error, "Queue full"
+    else
+      new_rear = (@rear + 1) % QUEUE_SIZE
+      @store[@rear] = element
+      @rear = new_rear
+    end
+    return @store
   end
 
-  def dequeue
-    raise NotImplementedError, "Not yet implemented"
+  def dequeue # remove from front 
+    removed = @store[@front] 
+    @store[@front] = nil
+    self.size == 0 ? @front = -1 : @front += 1
+    return removed 
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    return @store[@front]
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    size = 0
+    @store.each do |val|
+      if !val.nil?
+        size += 1
+      end
+    end
+    return size
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return true if self.size == 0
+    return false
   end
 
-  def to_s
-    return @store.to_s
+  def to_string
+    formatted_array = []
+    @store.each do |x|
+      if !x.nil?
+        formatted_array << x
+      end
+    end
+    return formatted_array.to_s
   end
-end
+end

lib/stack.rb

@@ -1,19 +1,24 @@
+require_relative './linked_list' 
+
 class Stack
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new()
   end
 
-  def push(element)
-    raise NotImplementedError, "Not yet implemented"
+  def push(element) # add to end
+    @store.add_last(element)
   end
 
-  def pop
-    raise NotImplementedError, "Not yet implemented"
+  def pop # remove from end
+    @store.remove_last if !self.empty?
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    @store.empty?
+  end
+
+  def peak_last 
+    return @store.get_last
   end
 
   def to_s

test/problems_test.rb

@@ -7,24 +7,24 @@
 describe "Test wave 3 problems" do
   describe "balanced" do
     it "Given balanced strings it should return true" do
-      skip
+      # skip
       expect(balanced('(({}))')).must_equal true
     end
 
     it "regards an empty string as balanced" do
-      skip
+      # skip
       expect(balanced('')).must_equal true
     end
 
     it "will return false for an unbalanced set of parens" do
-      skip
+      # skip
       expect(balanced('(()')).must_equal false
       expect(balanced('(()}')).must_equal false
       expect(balanced('([]]')).must_equal false
     end
 
     it "also works for {} and []" do
-      skip
+      # skip
       expect(balanced('[]')).must_equal true
       expect(balanced('{}')).must_equal true
     end

test/queue_test.rb

@@ -11,29 +11,28 @@
   end
 
   it "adds something to an empty Queue" do
-    skip
     q = Queue.new
     q.enqueue(10)
-    q.to_s.must_equal "[10]"
+    q.to_string.must_equal "[10]"
   end
 
   it "adds multiple somethings to a Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(10)
     q.enqueue(20)
     q.enqueue(30)
-    q.to_s.must_equal "[10, 20, 30]"
+    q.to_string.must_equal "[10, 20, 30]"
   end
 
   it "starts the size of a Queue at 0" do
-    skip
+    # skip
     q = Queue.new
     q.empty?.must_equal true
   end
 
   it "removes something from the Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(5)
     removed = q.dequeue
@@ -42,18 +41,18 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(5)
     q.enqueue(3)
     q.enqueue(7)
     removed = q.dequeue
     removed.must_equal 5
-    q.to_s.must_equal "[3, 7]"
+    q.to_string.must_equal "[3, 7]"
   end
 
   it "properly adjusts the size with enqueueing and dequeueing" do
-    skip
+    # skip
     q = Queue.new
     q.empty?.must_equal true
     q.enqueue(-1)
@@ -65,7 +64,7 @@
   end
 
   it "returns the front element in the Queue" do
-    skip
+    # skip
     q = Queue.new
     q.enqueue(40)
     q.enqueue(22)

test/stack_test.rb

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