Angela

lib/tree.rb

@@ -2,61 +2,142 @@ class TreeNode
   attr_reader :key, :value
   attr_accessor :left, :right
 
-   def initialize(key, val)
+  def initialize(key, val)
     @key = key
     @value = val
     @left = nil
     @right = nil
-   end
+  end
 end
 
 class Tree
   attr_reader :root
+
   def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(logn) because one side of the tree can be eliminated each time the new key is evaluated against the existing nodes data
+  # Space Complexity: O(1)
   def add(key, value)
-    raise NotImplementedError
+    new_node = TreeNode.new(key, value)
+    @root = new_node if @root.nil?
+    current = @root
+    add_helper(current, new_node)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def add_helper(current, new_node)
+    if current.nil?
+      return current = new_node
+    elsif new_node.key < current.key
+      current.left = add_helper(current.left, new_node)
+    elsif new_node.key > current.key
+      current.right = add_helper(current.right, new_node)
+    end
+    return current
+  end
+
+  # Time Complexity: O(logn) because one side of the tree can be eliminated each time the new key is evaluated against the existing nodes data
+  # Space Complexity: O(1)
   def find(key)
-    raise NotImplementedError
+    current = @root
+    return nil if current.nil?
+    return current.value if current.key == key
+    find_helper(current, key)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def find_helper(current, key)
+    if key == current.key
+      return current.value
+    elsif key < current.key
+      current.left = find_helper(current.left, key)
+    else
+      current.right = find_helper(current.right, key)
+    end
+  end
+
+  # Time Complexity: O(n) because each node will need to be visited and added to the final array
+  # Space Complexity: O(n) because the final array will contain the size of the tree
+  # left, root, right
   def inorder
-    raise NotImplementedError
+    array = []
+    return array if @root.nil?
+    inorder_helper(array, @root)
+    return array
+  end
+
+  def inorder_helper(array, node)
+    return if node.nil?
+    inorder_helper(array, node.left)
+    hash = { key: node.key, value: node.value }
+    array.push(hash)
+    inorder_helper(array, node.right)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) because each node will need to be visited and added to the final array
+  # Space Complexity: O(n) because the final array will contain the size of the tree
+  # root, left, right
   def preorder
-    raise NotImplementedError
+    return [] if @root.nil?
+    array = []
+    preorder_helper(@root, array)
+    return array
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def preorder_helper(node, array)
+    return if node.nil?
+    array.push({ key: node.key, value: node.value })
+    preorder_helper(node.left, array)
+    preorder_helper(node.right, array)
+  end
+
+  # Time Complexity: O(n) because each node will need to be visited and added to the final array
+  # Space Complexity: O(n) because the final array will contain the size of the tree
+  # left, right, root
   def postorder
-    raise NotImplementedError
+    array = []
+    return array if @root.nil?
+    postorder_helper(array, @root)
+    return array
+  end
+
+  def postorder_helper(array, node)
+    return if node.nil?
+    postorder_helper(array, node.left)
+    postorder_helper(array, node.right)
+    # hash = { key: node.key, value: node.value }
+    array.push({ key: node.key, value: node.value })
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) because worst case each node will need to be visited to be counted
+  # Space Complexity: O(1)
   def height
-    raise NotImplementedError
+    return 0 if @root.nil?
+    node = @root
+    return height_helper(@root)
+  end
+
+  def height_helper(node)
+    return 0 if node.nil?
+    left = height_helper(node.left)
+    right = height_helper(node.right)
+
+    if left >= right
+      return left + 1
+    else
+      return right + 1
+    end
   end
 
   # Optional Method
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity:
+  # Space Complexity:
   def bfs
-    raise NotImplementedError
+    array = []
+    return array if @root.nil?
+  end
+
+  def bfs_helper(node, level, array)
   end
 
   # Useful for printing

test/tree_test.rb

@@ -1,10 +1,10 @@
-require_relative 'test_helper'
-
+require_relative "test_helper"
+require "minitest/skip_dsl"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 describe Tree do
-  let (:tree) {Tree.new}
+  let (:tree) { Tree.new }
 
   let (:tree_with_nodes) {
     tree.add(5, "Peter")
@@ -37,23 +37,21 @@
     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"}]
+      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" }]
     end
   end
 
-
   describe "preorder" do
     it "will give an empty array for an empty tree" do
       expect(tree.preorder).must_equal []
     end
 
     it "will return the tree in preorder" do
-      expect(tree_with_nodes.preorder).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
-                                        {:key=>1, :value=>"Mary"}, {:key=>10, :value=>"Karla"}, 
-                                        {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+      expect(tree_with_nodes.preorder).must_equal [{ :key => 5, :value => "Peter" }, { :key => 3, :value => "Paul" },
+                                                   { :key => 1, :value => "Mary" }, { :key => 10, :value => "Karla" },
+                                                   { :key => 15, :value => "Ada" }, { :key => 25, :value => "Kari" }]
     end
   end
 
@@ -63,21 +61,35 @@
     end
 
     it "will return the tree in postorder" do
-      expect(tree_with_nodes.postorder).must_equal [{:key=>1, :value=>"Mary"}, {:key=>3, :value=>"Paul"}, 
-                                         {:key=>25, :value=>"Kari"}, {:key=>15, :value=>"Ada"}, 
-                                         {:key=>10, :value=>"Karla"}, {:key=>5, :value=>"Peter"}]
+      expect(tree_with_nodes.postorder).must_equal [{ :key => 1, :value => "Mary" }, { :key => 3, :value => "Paul" },
+                                                    { :key => 25, :value => "Kari" }, { :key => 15, :value => "Ada" },
+                                                    { :key => 10, :value => "Karla" }, { :key => 5, :value => "Peter" }]
+    end
+  end
+
+  describe "height" do
+    it "will return 0 if tree is empty" do
+      expect(tree.height).must_equal 0
+    end
+
+    it "will return the height of the tree" do
+      expect(tree_with_nodes.height).must_equal 4
+      tree_with_nodes.add(2, "bob")
+      expect(tree_with_nodes.height).must_equal 4
+      tree_with_nodes.add(50, "angela")
+      expect(tree_with_nodes.height).must_equal 5
     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
 
     it "will return an array of a level-by-level output of the tree" do
-      expect(tree_with_nodes.bfs).must_equal [{:key=>5, :value=>"Peter"}, {:key=>3, :value=>"Paul"}, 
-                                   {:key=>10, :value=>"Karla"}, {:key=>1, :value=>"Mary"}, 
-                                   {:key=>15, :value=>"Ada"}, {:key=>25, :value=>"Kari"}]
+      expect(tree_with_nodes.bfs).must_equal [{ :key => 5, :value => "Peter" }, { :key => 3, :value => "Paul" },
+                                              { :key => 10, :value => "Karla" }, { :key => 1, :value => "Mary" },
+                                              { :key => 15, :value => "Ada" }, { :key => 25, :value => "Kari" }]
     end
   end
-end
+end