Sarah

lib/problems.rb

@@ -1,9 +1,18 @@
-require_relative './stack.rb'
+require_relative "./stack.rb"
 
 def balanced(string)
-  raise NotImplementedError, "Not implemented yet"
+  stack = Stack.new
+  pairs = { ")" => "(", "]" => "[", "}" => "{" }
+  string.each_char do |bracket|
+    if pairs.values.include?(bracket)
+      stack.push(bracket)
+    else
+      return false if stack.empty? or pairs[bracket] != stack.pop()
+    end
+  end
+  return stack.empty?
 end
 
 def evaluate_postfix(postfix_expression)
   raise NotImplementedError, "Not implemented yet"
-end
+end

lib/queue.rb

@@ -1,16 +1,33 @@
 class Queue
+  QUEUE_SIZE = 20
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    # @store = ..
+    @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 Error, "Q Full"
+    else # not empty
+      new_rear = (@rear + 1) % QUEUE_SIZE
+      @store[@rear] = element
+      @rear = new_rear
+    end
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    raise Error, "Q Empty" if @front == -1
+    value = @store[@front]
+    @store[@front] = nil
+    @front = (@front + 1) % QUEUE_SIZE
+    @front = @rear = -1 if @front == @rear
+    return value
   end
 
   def front
@@ -22,10 +39,10 @@ def size
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @rear == -1
   end
 
   def to_s
-    return @store.to_s
+    return @store[@front...@rear].to_s
   end
 end

lib/stack.rb

@@ -1,19 +1,20 @@
+require_relative "linked_list.rb"
+
 class Stack
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = LinkedList.new()
   end
 
   def push(element)
-    raise NotImplementedError, "Not yet implemented"
+    @store.add_last(element)
   end
 
   def pop
-    raise NotImplementedError, "Not yet implemented"
+    @store.remove_last()
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @store.empty?()
   end
 
   def to_s

test/problems_test.rb

@@ -1,32 +1,28 @@
-require 'minitest/autorun'
-require 'minitest/reporters'
-require_relative '../lib/problems'
+require "minitest/autorun"
+require "minitest/reporters"
+require_relative "../lib/problems"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 describe "Test wave 3 problems" do
   describe "balanced" do
     it "Given balanced strings it should return true" do
-      skip
-      expect(balanced('(({}))')).must_equal true
+      expect(balanced("(({}))")).must_equal true
     end
 
     it "regards an empty string as balanced" do
-      skip
-      expect(balanced('')).must_equal true
+      expect(balanced("")).must_equal true
     end
 
     it "will return false for an unbalanced set of parens" do
-      skip
-      expect(balanced('(()')).must_equal false
-      expect(balanced('(()}')).must_equal false
-      expect(balanced('([]]')).must_equal false
+      expect(balanced("(()")).must_equal false
+      expect(balanced("(()}")).must_equal false
+      expect(balanced("([]]")).must_equal false
     end
 
     it "also works for {} and []" do
-      skip
-      expect(balanced('[]')).must_equal true
-      expect(balanced('{}')).must_equal true
+      expect(balanced("[]")).must_equal true
+      expect(balanced("{}")).must_equal true
     end
   end
 
@@ -49,4 +45,4 @@
       expect(evaluate_postfix("62/5+")).must_equal 8
     end
   end
-end
+end

test/queue_test.rb

@@ -1,6 +1,6 @@
-require 'minitest/autorun'
-require 'minitest/reporters'
-require_relative '../lib/queue'
+require "minitest/autorun"
+require "minitest/reporters"
+require_relative "../lib/queue"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
@@ -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)
@@ -65,12 +59,11 @@
   end
 
   it "returns the front element in the Queue" do
-    skip
     q = Queue.new
     q.enqueue(40)
     q.enqueue(22)
     q.enqueue(3)
     q.dequeue
     expect(q.dequeue).must_equal 22
   end
-end
+end

test/stack_test.rb

@@ -1,6 +1,6 @@
-require 'minitest/autorun'
-require 'minitest/reporters'
-require_relative '../lib/stack'
+require "minitest/autorun"
+require "minitest/reporters"
+require_relative "../lib/stack"
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 describe "Test Stack Implementation" do
@@ -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)
@@ -50,4 +45,4 @@
     removed.must_equal 7
     s.to_s.must_equal "[5, 3]"
   end
-end
+end