Laneia

lib/tree.rb

@@ -2,61 +2,137 @@ 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
+
+  def add(key, value)
+    if key == @key
+      return
+    elsif key < @key
+      left.nil? ? @left = TreeNode.new(key, value) : left.add(key, value)
+    elsif key > @key
+      right.nil? ? @right = TreeNode.new(key, value) : right.add(key, value)
+    end
+  end
+
+  def find(key)
+    if key == @key
+      return @value
+    elsif key < @key
+      left.nil? ? nil : left.find(key)
+    elsif key > @key
+      right.nil? ? nil : right.find(key)
+    end
+  end
+
+  def inorder(array)
+    left.inorder(array) unless left.nil?
+    array << {key: @key, value: @value}
+    right.inorder(array) unless right.nil?
+  end
+
+  def preorder(array)
+    array << {key: @key, value: @value}
+
+    if left
+      left.preorder(array)
+    end
+
+    if right
+      right.preorder(array)
+    end
+  end
+
+  def postorder(array)
+    if left
+      left.postorder(array)
+    end
+
+    if right
+      right.postorder(array)
+    end
+    array << {key: @key, value: @value}
+  end
 end
 
 class Tree
   attr_reader :root
+
   def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) if balanced tree, O(n) if unbalanced, n = # nodes in tree
+  # Space Complexity: O(log n) if balanced tree, O(n) if unbalanced, n = # nodes in tree
   def add(key, value)
-    raise NotImplementedError
+    if root.nil?
+      @root = TreeNode.new(key, value)
+    else
+      root.add(key, value)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n) if balanced tree, O(n) if unbalanced, n = # nodes in tree
+  # Space Complexity: O(log n) if balanced tree, O(n) if unbalanced, n = # nodes in tree
   def find(key)
-    raise NotImplementedError
+    if root.nil?
+      return nil
+    else
+      root.find(key)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n),n = # nodes in tree
+  # Space Complexity: O(n), n = # nodes in tree
   def inorder
-    raise NotImplementedError
+    array = []
+    if root.nil?
+      return array
+    else
+      root.inorder(array)
+      return array
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n), n = # nodes in tree
+  # Space Complexity: O(n), n = # nodes in tree
   def preorder
-    raise NotImplementedError
+    array = []
+    if root.nil?
+      return array
+    else
+      root.preorder(array)
+      return array
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n), n = # nodes in tree
+  # Space Complexity: O(n), n = # nodes in tree
   def postorder
-    raise NotImplementedError
+    array = []
+    if root.nil?
+      return array
+    else
+      root.postorder(array)
+      return array
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
-  def height
-    raise NotImplementedError
-  end
+  # Time Complexity: O(n), n = # nodes in tree
+  # Space Complexity: O(1)
+  def height(current = @root)
+    if current
+      lh = height(current.left)
+      rh = height(current.right)
 
-  # Optional Method
-  # Time Complexity: 
-  # Space Complexity: 
-  def bfs
-    raise NotImplementedError
+      (lh > rh ? lh : rh) + 1
+    else
+      0
+    end
   end
 
   # Useful for printing

test/tree_test.rb

@@ -1,10 +1,9 @@
-require_relative 'test_helper'
-
+require_relative "test_helper"
 
 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 +36,21 @@
     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
 
@@ -63,12 +60,12 @@
     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 "returns 0 for an empty tree" do
       expect(tree.height).must_equal 0
@@ -78,16 +75,4 @@
       expect(tree_with_nodes.height).must_equal 4
     end
   end
-
-  describe "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"}]
-    end
-  end
 end