Niv

lib/problems.rb

@@ -1,7 +1,26 @@
 require_relative './stack.rb'
 
 def balanced(string)
-  raise NotImplementedError, "Not implemented yet"
+  pairs = {")" => "(", "}" => "{", "]"=>"["}
+  character_stack = Stack.new
+  i = 0
+  while i < string.length
+    if pairs.has_value?(string[i]) == true
+      character_stack.push(string[i])
+    else
+      if character_stack.pop != pairs[string[i]]
+        return false
+      end
+    end
+    i+=1
+  end
+
+  if character_stack.empty? == true
+    return true
+  else
+    return false
+  end
+
 end
 
 def evaluate_postfix(postfix_expression)

lib/queue.rb

@@ -1,28 +1,33 @@
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = []
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    @store.push(element)
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    removed = @store[0]
+    @store = @store[1..-1]
+    return removed
   end
 
   def front
-    raise NotImplementedError, "Not yet implemented"
+    return @store[0]
   end
 
   def size
-    raise NotImplementedError, "Not yet implemented"
+    return @store.length
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    if @store.length > 0
+      return false
+    else
+      return true
+    end
   end
 
   def to_s

lib/stack.rb

@@ -1,19 +1,25 @@
+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"
+    removed = @store.remove_last
+    return removed
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    if @store.length >  0
+      return false
+    else
+      return true
+    end
   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
+
       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 +11,13 @@
   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 +26,13 @@
   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 +41,7 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
+
     q = Queue.new
     q.enqueue(5)
     q.enqueue(3)
@@ -53,7 +52,7 @@
   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 +64,7 @@
   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 +10,14 @@
   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 +26,13 @@
   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 +41,7 @@
   end
 
   it "removes the right something (LIFO)" do
-    skip
+
     s = Stack.new
     s.push(5)
     s.push(3)