diff --git a/lib/tree.rb b/lib/tree.rb index c0d4b51..a161ff0 100644 --- a/lib/tree.rb +++ b/lib/tree.rb @@ -2,63 +2,162 @@ 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 + @parent = nil + end end class Tree attr_reader :root + def initialize @root = nil end - # Time Complexity: - # Space Complexity: + # Time Complexity: O(logn) + # Space Complexity: O(1) def add(key, value) - raise NotImplementedError + new_node = TreeNode.new(key, value) + return @root = new_node unless @root + add_node(@root, new_node) + end + + def add_node(root, new_node) + if new_node.key < root.key + return root.left = new_node unless root.left + add_node(root.left, new_node) + elsif new_node.key > root.key + return root.right = new_node unless root.right + add_node(root.right, new_node) + end end - # Time Complexity: - # Space Complexity: + # Time Complexity: O(n) / O(logn) + # Space Complexity: O(1) def find(key) - raise NotImplementedError + return find_helper(key, @root) end - # Time Complexity: - # Space Complexity: + def find_helper(key, node) + return nil unless node + if key == node.key + return node.value + elsif key < node.key + find_helper(key, node.left) + else key > node.key + find_helper(key, node.right) end + end + + # Time Complexity: O(n) + # Space Complexity: O(n) def inorder - raise NotImplementedError + array = [] + inorder_helper(array, @root) + end + + def inorder_helper(array, node) + return array unless node + inorder_helper(array, node.left) + node_kv = {} + node_kv[:key] = node.key + node_kv[:value] = node.value + array.push(node_kv) + inorder_helper(array, node.right) end - # Time Complexity: - # Space Complexity: + # Time Complexity: O(n) + # Space Complexity: O(n) def preorder - raise NotImplementedError + array = [] + return preorder_helper(array, @root) end - # Time Complexity: - # Space Complexity: + def preorder_helper(array, node) + return array unless node + node_kv = {} + node_kv[:key] = node.key + node_kv[:value] = node.value + array.push(node_kv) + preorder_helper(array, node.left) + preorder_helper(array, node.right) + end + + # Time Complexity: + # Space Complexity: def postorder - raise NotImplementedError + array = [] + postorder_helper(@root, array) + return array + end + + def postorder_helper(root, array) + return unless root + postorder_helper(root.left, array) + postorder_helper(root.right, array) + array.push({ key: root.key, value: root.value }) end - # Time Complexity: - # Space Complexity: + # Time Complexity: + # Space Complexity: def height - raise NotImplementedError + height_counter(@root) + end + + def height_counter(node) + return 0 unless node + left_counter = height_counter(node.left) + right_counter = height_counter(node.right) + counter = left_counter > right_counter ? left_counter : right_counter + return counter += 1 end # Optional Method - # Time Complexity: - # Space Complexity: + # Time Complexity: O(n) + # Space Complexity: O(2n) + + # i know there will be less lines of code if q is implemented, please see commented psuedocode below for q implementation def bfs - raise NotImplementedError + return [] unless @root + array = [@root] + i = 0 + current = @root + length = 1 + until (i == length - 1) && (current.left == nil) && (current.right == nil) + if current.left + array.push(current.left) + length += 1 + end + if current.right + array.push(current.right) + length += 1 + end + i += 1 + current = array[i] + end + return array.map do |node| + { key: node.key, value: node.value } + end end + # BFS USING QUEUE + # Time Complexity: O(n) + # Space Complexity: O(2n) + # def bfs + # q = Queue.new(@root) + # array = [] + # until q is_empty + # current = q.dequeue + # array.push({key: current.key, value: current.value }) + # q.enqueue(current.left) if current.left + # q.enqueue(current.right) if current.right + # end + # return array + # end + # Useful for printing def to_s return "#{self.inorder}" diff --git a/test/test_helper.rb b/test/test_helper.rb index 02213c1..0b0c40f 100644 --- a/test/test_helper.rb +++ b/test/test_helper.rb @@ -3,6 +3,6 @@ require 'minitest/autorun' require 'minitest/reporters' -Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new +Minitest::Reporters.use! require_relative '../lib/tree' diff --git a/test/tree_test.rb b/test/tree_test.rb index 222b693..0d4256b 100644 --- a/test/tree_test.rb +++ b/test/tree_test.rb @@ -1,10 +1,10 @@ -require_relative 'test_helper' - +require_relative "test_helper" +require "pry" 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 @@ -63,12 +61,12 @@ 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 @@ -85,9 +83,9 @@ 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