Kristina - Leaves

lib/problems.rb

@@ -3,7 +3,24 @@
 # Time Complexity: ?
 # Space Complexity: ?
 def balanced(string)
-  raise NotImplementedError, "Not implemented yet"
+  stack = Stack.new
+  pairs = {
+    ')'=> '(',
+    '}'=> '{',
+    ']'=> '['
+  }
+
+  string.each_char do |char|
+    if close.keys.include?(char)
+      stack.push(char)
+    elsif close.values.include?(char)
+      return false if stack.empty?
+      element = stack.pop
+      return false if char != close[element]
+    end
+  end
+
+  return stack.empty? 
 end
 
 # Time Complexity: ?

lib/queue.rb

@@ -1,16 +1,39 @@
 class Queue
 
   def initialize
-    # @store = ...
-    raise NotImplementedError, "Not yet implemented"
+    @store = Array.new(100)
+    @front = @back = -1
   end
 
   def enqueue(element)
-    raise NotImplementedError, "Not yet implemented"
+    if @front == -1 && @back == -1
+      @front = @back = 0
+    end
+
+    if @front == @back
+    end
+
+    @store[@back] = element 
+    @back = (@back + 1) % @store.length 
   end
 
   def dequeue
-    raise NotImplementedError, "Not yet implemented"
+    if @front == @back
+      return "queue is empty"
+    end
+
+    data = @store[@front]
+    @store[@front] = nil
+
+    if @front == @back
+      @front = @back = -1
+    elsif @front == @store.length - 1
+      @front = 0
+    else
+      @front += 1
+    end
+
+    return data
   end
 
   def front
@@ -22,10 +45,13 @@ def size
   end
 
   def empty?
-    raise NotImplementedError, "Not yet implemented"
+    if @front == @back
+      return true
+    end
   end
 
   def to_s
+    @store.delete(nil)
     return @store.to_s
   end
 end

lib/stack.rb

@@ -1,19 +1,18 @@
 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

@@ -7,45 +7,38 @@
 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
 
     it "also works if the string has opens and closes in the beginning and end" do
-      skip
       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)