Fire - Noor

lib/tree.rb

@@ -16,40 +16,40 @@ def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
-  def add(key, value)
-    raise NotImplementedError
+  # Time Complexity: O(log n)
+  # Space Complexity: O(log n)
+  def add(key, value = nil)
+    @root = add_helper(@root, key, value)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n)
+  # Space Complexity: O(log n)
   def find(key)
-    raise NotImplementedError
+    find_helper(@root,key)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def inorder
-    raise NotImplementedError
+    inorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def preorder
-    raise NotImplementedError
+    preorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def postorder
-    raise NotImplementedError
+    postorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def height
-    raise NotImplementedError
+    height_helper(@root)
   end
 
   # Optional Method
@@ -64,3 +64,74 @@ def to_s
     return "#{self.inorder}"
   end
 end
+
+# Helper methods
+def add_helper(current, key, value = nil)
+  if current.nil?
+    current = TreeNode.new(key, value)
+  elsif key >= current.key
+    current.right = add_helper(current.right, key, value)
+  else
+    current.left = add_helper(current.left, key, value)
+  end
+
+  return current
+
+end
+
+def find_helper(current, key)
+  return nil if current.nil?
+
+  if key == current.key
+    return current.value
+  elsif key > current.key
+    return find_helper(current.right, key)
+  elsif key < current.key
+    return find_helper(current.left, key)
+  end
+end
+
+def inorder_helper(node, array)
+  # Left, Current, Right
+  return array if node.nil?
+
+  inorder_helper(node.left, array)
+  array << {
+    key: node.key,
+    value: node.value
+  }
+  inorder_helper(node.right, array)
+end
+
+def preorder_helper(node, array)
+  # Current, Left, Right
+  return array if node.nil?
+
+  array << {
+    key: node.key,
+    value: node.value
+  }
+  preorder_helper(node.left, array)
+  preorder_helper(node.right, array)
+end
+
+def postorder_helper(node, array)
+  # Left, Right, Current
+  return array if node.nil?
+
+  postorder_helper(node.left, array)
+  postorder_helper(node.right, array)
+  array << {
+    key: node.key,
+    value: node.value
+  }
+end
+
+def height_helper(node)
+  return 0 if node.nil?
+
+  right_count = height_helper(node.right) + 1
+  left_count = height_helper(node.left) + 1
+
+  return [right_count, left_count].max
+end

test/tree_test.rb

@@ -69,7 +69,7 @@
     end
   end
 
-  describe "breadth first search" do
+  xdescribe "breadth first search" do
     it "will give an empty array for an empty tree" do
       expect(tree.bfs).must_equal []
     end