Time - Hannah T

Gemfile

@@ -1,10 +1,9 @@
 # frozen_string_literal: true
 source "https://rubygems.org"
 
-gem 'rake'
-gem 'minitest'
-gem 'minitest-spec'
-gem 'minitest-reporters'
+gem "rake"
+gem "minitest"
+gem "minitest-spec"
+gem "minitest-reporters"
 gem "pry"
-gem 'minitest-skip'
-
+gem "minitest-skip"

Rakefile

@@ -1,9 +1,9 @@
-require 'rake/testtask'
+require "rake/testtask"
 
 Rake::TestTask.new do |t|
   t.libs = ["lib"]
   t.warning = true
-  t.test_files = FileList['test/*_test.rb']
+  t.test_files = FileList["test/*_test.rb"]
 end
 
 task default: :test

lib/heap_sort.rb

@@ -1,8 +1,17 @@
-
+require_relative "./min_heap"
 
 # This method uses a heap to sort an array.
-# Time Complexity:  ?
-# Space Complexity: ?
-def heap_sort(list)
-  raise NotImplementedError, "Method not implemented yet..."
-end
+# Time Complexity:  O(long n)
+# Space Complexity: O(n)
+def heapsort(list)
+  min_heap = MinHeap.new()
+  list.each do |item|
+    min_heap.add(item)
+  end
+  empty_arr = []
+
+  list.length.times do
+    empty_arr << min_heap.remove()
+  end
+  return empty_arr
+end

lib/min_heap.rb

@@ -8,27 +8,56 @@ def initialize(key, value)
 end
 
 class MinHeap
-
   def initialize
     @store = []
   end
 
   # This method adds a HeapNode instance to the heap
-  # Time Complexity: ?
-  # Space Complexity: ?
+  # Time Complexity: O (log n)
+  # Space Complexity: O (n)
   def add(key, value = key)
-    raise NotImplementedError, "Method not implemented yet..."
+    heap_node = HeapNode.new(key, value)
+    @store.push(heap_node)
+    curent_index = @store.length - 1
+    parent_index = (curent_index - 1) / 2
+    while heap_node.key < @store[parent_index].key
+      swap(curent_index, parent_index)
+      curent_index = parent_index
+      parent_index = (curent_index - 1) / 2
+      break if parent_index < 0
+    end
   end
 
   # This method removes and returns an element from the heap
   #   maintaining the heap structure
-  # Time Complexity: ?
-  # Space Complexity: ?
+  # Time Complexity: O (log n)
+  # Space Complexity: O (n)
   def remove()
-    raise NotImplementedError, "Method not implemented yet..."
+    return nil if @store.empty?
+    swap(0, @store.length - 1)
+    result = @store.pop
+    curent_index = 0
+    left_child_index = 1
+    right_child_index = 2
+    while @store[left_child_index] || @store[right_child_index]
+      if @store[right_child_index] && @store[right_child_index].key < @store[left_child_index].key && @store[right_child_index].key < @store[curent_index].key
+        swap(curent_index, right_child_index)
+        curent_index = right_child_index
+      elsif @store[right_child_index] && @store[right_child_index].key > @store[left_child_index].key && @store[left_child_index].key < @store[curent_index].key
+        swap(curent_index, left_child_index)
+        curent_index = left_child_index
+      elsif @store[left_child_index] && @store[left_child_index].key < @store[curent_index].key
+        swap(curent_index, left_child_index)
+        curent_index = left_child_index
+      else
+        break
+      end
+      left_child_index = (curent_index * 2) + 1
+      right_child_index = (curent_index * 2) + 2
+    end
+    return result.value
   end
 
-
   # Used for Testing
   def to_s
     return "[]" if @store.empty?
@@ -39,15 +68,15 @@ def to_s
     end
 
     output += @store.last.value + "]"
-      
+
     return output
   end
 
   # This method returns true if the heap is empty
-  # Time complexity: ?
-  # Space complexity: ?
+  # Time complexity: O (1)
+  # Space complexity: O (1)
   def empty?
-    raise NotImplementedError, "Method not implemented yet..."
+    return @store.empty?
   end
 
   private
@@ -58,14 +87,28 @@ def empty?
   # Time complexity: ?
   # Space complexity: ?
   def heap_up(index)
-
+    return nil if @store.empty?
+    parent_index = (index - 1)/2
+    if @store[index].key >= @store[parent_index].key || index == 0
+      return @store
+    else
+      swap(index, parent_index)
+      heap_up(parent_index)
+    end
   end
 
-  # This helper method takes an index and 
+  # This helper method takes an index and
   #  moves it up the heap if it's smaller
   #  than it's parent node.
   def heap_down(index)
-    raise NotImplementedError, "Method not implemented yet..."
+    min = index
+    left, right = 2 * index + 1, 2 * index + 2
+    left < @store.length && @store[left].key < @store[min].key ? min = left : nil
+    right < @store.length && @store[right].key < @store[min].key ? min = right : nil
+    if min != index
+      swap(index, min)
+      heap_down(min)
+    end
   end
 
   # If you want a swap method... you're welcome
@@ -74,4 +117,4 @@ def swap(index_1, index_2)
     @store[index_1] = @store[index_2]
     @store[index_2] = temp
   end
-end
+end

test/heapsort_test.rb

@@ -1,8 +1,8 @@
 require_relative "test_helper"
 
-xdescribe "heapsort" do
+describe "heapsort" do
   it "sorts an empty array" do
-    # Arrange 
+    # Arrange
     list = []
 
     # Act
@@ -13,7 +13,7 @@
   end
 
   it "can sort a 1-element array" do
-    # Arrange 
+    # Arrange
     list = [5]
 
     # Act
@@ -22,15 +22,15 @@
     # Assert
     expect(result).must_equal [5]
   end
-  
+
   it "can sort a 5-element array" do
-    # Arrange 
+    # Arrange
     list = [5, 27, 3, 16, -50]
 
     # Act
     result = heapsort(list)
 
     # Assert
     expect(result).must_equal [-50, 3, 5, 16, 27]
-  end  
-end
+  end
+end

test/min_heap_test.rb

@@ -1,9 +1,9 @@
 require_relative "test_helper"
 
 describe "Heap" do
-  let(:heap) {MinHeap.new}
+  let(:heap) { MinHeap.new }
   it "can be created" do
-    
+
     # Assert
     expect(heap).must_be_instance_of MinHeap
   end
@@ -52,30 +52,30 @@
   end
 
   it "can remove nodes in the proper order" do
-   # Arrange
-   heap.add(3, "Pasta")
-   heap.add(6, "Soup")
-   heap.add(1, "Pizza")
-   heap.add(0, "Donuts")
-   heap.add(16, "Cookies")
-   heap.add(57, "Cake")
+    # Arrange
+    heap.add(3, "Pasta")
+    heap.add(6, "Soup")
+    heap.add(1, "Pizza")
+    heap.add(0, "Donuts")
+    heap.add(16, "Cookies")
+    heap.add(57, "Cake")
 
-   # Act
-   removed = heap.remove
+    # Act
+    removed = heap.remove
 
-   # Assert
-   expect(removed).must_equal "Donuts"
+    # Assert
+    expect(removed).must_equal "Donuts"
 
-   # Another Act
-   removed = heap.remove
+    # Another Act
+    removed = heap.remove
 
-   # Another assert
-   expect(removed).must_equal "Pizza"
+    # Another assert
+    expect(removed).must_equal "Pizza"
 
-  # Another Act
-  removed = heap.remove
+    # Another Act
+    removed = heap.remove
 
-  # Another assert
-  expect(removed).must_equal "Pasta"
+    # Another assert
+    expect(removed).must_equal "Pasta"
   end
-end
+end

test/test_helper.rb

@@ -1,9 +1,9 @@
-require 'minitest'
-require 'minitest/autorun'
-require 'minitest/reporters'
+require "minitest"
+require "minitest/autorun"
+require "minitest/reporters"
 require "minitest/skip_dsl"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
-require_relative '../lib/min_heap'
-require_relative '../lib/heap_sort'
+require_relative "../lib/min_heap"
+require_relative "../lib/heap_sort"