Ports - Ngoc

lib/linked_list.rb

@@ -34,11 +34,12 @@ def add_first(value)
 
     def remove_first()
       raise ArgumentError, "Empty" if self.empty?
-
-      value = @head.data
-      @head = @head.next
-      @head.previous = nil
-      return value
+
+        value = @head.data
+        @head.previous = nil
+        @head = @head.next
+
+        return value
     end
 
     def empty?

lib/problems.rb

@@ -1,7 +1,22 @@
 require_relative './stack.rb'
 
 def balanced(string)
-  raise NotImplementedError, "Not implemented yet"
+  stack = Stack.new
+  string.each_char do |char|
+    if char == "{" || char == "[" || char == "("
+      stack.push(char)  
+    end
+    if (stack.get_last() == "{" && char == "}") ||
+      (stack.get_last() == "[" && char == "]") ||
+      (stack.get_last() == "(" && char == ")")
+      stack.pop()
+    end
+  end
+  if stack.length() == 0 
+    return true
+  else
+    return false
+  end
 end
 
 def evaluate_postfix(postfix_expression)

lib/queue.rb

@@ -1,16 +1,40 @@
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = Array.new(10)
+    @front = @rear = -1
+    @size = 0
+    @capacity = 10
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    if @size == @capacity
+    return
+    else
+      if @front == -1
+        @front = 0
+      end
+      @rear = (@rear + 1) % @capacity
+      @store[@rear] = element
+      @size += 1
+    end
   end
 
-  def dequeue
-    raise NotImplementedError, "Not yet implemented"
+  def dequeue 
+    if empty?
+      return
+    elsif @front == @rear
+      removed_element = @store[@front]
+      @front = -1
+      @rear = -1
+      @size -= 1
+      return removed_element
+    else
+      removed_element = @store[@front]
+      @front = (@front + 1) % @capacity
+      @size -= 1
+      return removed_element
+    end
   end
 
   def front
@@ -22,10 +46,21 @@ def size
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    if @size == 0
+      return true
+    else
+      return false
+    end
   end
 
   def to_s
-    return @store.to_s
+    if @size == 0
+      return [].to_s
+    elsif @front <= @rear
+      return @store[@front..@rear].to_s
+    else
+      new_array = @store[@front .. @capacity -1] + @store[0..@rear]
+      return new_array.to_s
+    end
   end
 end

lib/stack.rb

@@ -1,19 +1,29 @@
+require '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"
+    return nil if self.empty?
+    item = @store.remove_last()
+    return item
+  end
+
+  def get_last
+    return @store.get_last()
+  end
+
+  def length
+    return @store.length
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    return @store.empty?
   end
 
   def to_s

test/problems_test.rb

@@ -7,40 +7,34 @@
 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
   end
 
   describe "postfix" do
     it "can add a 2 numbers together" do
-      skip
       expect(evaluate_postfix("34+")).must_equal 7
       expect(evaluate_postfix("34*")).must_equal 12
       expect(evaluate_postfix("34-")).must_equal -1
       expect(evaluate_postfix("34/")).must_equal 0
     end
 
     it "can add a evaluate a more complicated expression" do
-      skip
       expect(evaluate_postfix("34+2*")).must_equal 14
       expect(evaluate_postfix("34*2/")).must_equal 6
       expect(evaluate_postfix("34-1+")).must_equal 0

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)