Nara

lib/problems.rb

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

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
+      @front = 0
+      @rear = 1
+      @store[@front] = element
+    elsif @front == (@rear + 1) % QUEUE_SIZE
+      raise Error, "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 == @rear
+      @front = @rear = -1
+      raise Error, "Queue is empty"
+    else
+      new_front = (@front + 1) % QUEUE_SIZE
+      old_front = @store[@front]
+      @store[@front] = nil
+      @front = new_front
+      return old_front
+    end
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    return @strore[@front]
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    return @store.length
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    if @store[@front...@rear].length == 0 
+      return true
+    else 
+      return false
+    end
   end
 
   def to_s
-    return @store.to_s
+    return @store[@front...@rear].to_s
   end
 end

lib/stack.rb

@@ -1,19 +1,19 @@
+require 'linked_list'
 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"
+    @store.empty?
   end
 
   def to_s

test/problems_test.rb

@@ -7,24 +7,20 @@
 describe "Test wave 3 problems" do
   describe "balanced" do
     it "Given balanced strings it should return true" do
-      skip
       expect(balanced('(({}))')).must_equal true
     end
 
     it "regards an empty string as balanced" do
-      skip
       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
     end
 
     it "also works for {} and []" do
-      skip
       expect(balanced('[]')).must_equal true
       expect(balanced('{}')).must_equal true
     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)