Water - Kareha

lib/tree.rb

@@ -16,51 +16,137 @@ def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
-  def add(key, value)
-    raise NotImplementedError
+  # Time Complexity: O(logn)
+  # Space Complexity: O(logn)
+  def add(key, value = nil)
+    unless root
+      @root = TreeNode.new(key, value)
+    else
+      add_helper(@root, key, value)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def add_helper(current, key, value)
+    return TreeNode.new(key, value) unless current
+
+    if key < current.key
+      current.left = add_helper(current.left, key, value)
+    else
+      current.right = add_helper(current.right, key, value)
+    end
+
+    return current
+
+  end
+
+  # Time Complexity: O(logn)
+  # Space Complexity: O(logn)
   def find(key)
-    raise NotImplementedError
+    return find_helper(@root, key)
+  end
+
+  def find_helper(current, key)
+    return current unless current
+    return current.value if key == current.key
+
+    if current.key < key
+      find_helper(current.right, key)
+    else
+      find_helper(current.left, key)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def inorder
-    raise NotImplementedError
+    tree_in_order = []
+    return inorder_helper(tree_in_order, @root)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def inorder_helper(tree, current)
+    return tree unless current
+
+    inorder_helper(tree, current.left)
+    tree.push({:key=>current.key, :value=>current.value})
+    inorder_helper(tree, current.right)
+
+    return tree
+  end
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def preorder
-    raise NotImplementedError
+    tree_pre_order = []
+    return preorder_helper(@root, tree_pre_order)
+  end
+
+  def preorder_helper(current, tree)
+    return tree unless current
+
+    tree.push({:key=>current.key, :value=>current.value})
+    preorder_helper(current.left, tree)
+    preorder_helper(current.right, tree)
+
+    return tree
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def postorder
-    raise NotImplementedError
+    tree_post_order = []
+    return postorder_helper(@root, tree_post_order)
+  end
+
+  def postorder_helper(current, tree)
+    return tree unless current
+
+    postorder_helper(current.left, tree)
+    postorder_helper(current.right, tree)
+    tree.push({:key=>current.key, :value=>current.value})
+
+    return tree
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
   def height
-    raise NotImplementedError
+    return height_helper(@root)
+  end
+
+  def height_helper(current)
+    return 0 unless current
+
+    left_height = height_helper(current.left)
+    right_height = height_helper(current.right)
+
+    return left_height < right_height ? right_height + 1 : left_height + 1
   end
 
   # Optional Method
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n*m)
+  # Space Complexity: O(n)
   def bfs
-    raise NotImplementedError
+    q = []
+    tree_bfs = []
+    return tree_bfs unless @root
+
+    q.push(@root)
+
+    until q.empty?
+      current = q.shift
+
+      tree_bfs.push({:key=>current.key, :value=>current.value})
+
+      q.push(current.left) if current.left
+      q.push(current.right) if current.right
+    end
+
+    return tree_bfs
+
   end
 
   # Useful for printing
   def to_s
     return "#{self.inorder}"
   end
-end
+end

test/tree_test.rb

@@ -37,7 +37,6 @@
     end
 
     it "will return the tree in order" do
-
       expect(tree_with_nodes.inorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
                                        {:key=>5, :value=>"Peter"}, {:key=>10, :value=>"Karla"}, 
                                        {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
@@ -95,8 +94,8 @@
       expect(my_tree.height).must_equal 1
     end
 
-    it "will report the height for a balanced tree" do
-      expect(tree_with_nodes.height).must_equal 3
+    it "will report the height for a tree with height 4 on right and 3 on left" do
+      expect(tree_with_nodes.height).must_equal 4
     end
 
     it "will report the height for unbalanced trees" do