fuego-blaine

lib/heap_sort.rb

@@ -1,8 +1,18 @@
 
 
 # This method uses a heap to sort an array.
-# Time Complexity:  ?
-# Space Complexity: ?
-def heap_sort(list)
-  raise NotImplementedError, "Method not implemented yet..."
+# Time Complexity:  O(n)
+# Space Complexity: O(n)
+def heapsort(list)
+  # raise NotImplementedError, "Method not implemented yet..."
+  mamasHeap = MinHeap.new()
+  list.each do |e|
+    mamasHeap.add(e)
+  end
+  # p mamasHeap
+  new_list = []
+  while !mamasHeap.empty?
+    new_list << mamasHeap.remove()
+  end
+  return new_list
 end

lib/min_heap.rb

@@ -14,18 +14,31 @@ def initialize
   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..."
+    # raise NotImplementedError, "Method not implemented yet..."
+    # add new node into array (@store) <- shovel or push
+    # run the heap_up( arr.length - 1 or @store[-1])
+    @store.push(HeapNode.new(key, value))
+    heap_up(@store.length - 1)
   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..."
+    # raise NotImplementedError, "Method not implemented yet..."
+    if @store.empty?
+      return nil
+    end
+
+    swap(0, @store.length - 1)
+    result = @store.pop #pop removes the last item in an array
+
+    heap_down(0) unless @store.empty?
+    return result.value
   end
 
 
@@ -44,28 +57,48 @@ def to_s
   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..."
+    # raise NotImplementedError, "Method not implemented yet..."
+    return true if @store.empty?
   end
 
   private
 
   # This helper method takes an index and
   #  moves it up the heap, if it is less than it's parent node.
   #  It could be **very** helpful for the add method.
-  # Time complexity: ?
-  # Space complexity: ?
-  def heap_up(index)
-
+  # Time complexity: O(logn)
+  # Space complexity: O(n)
+  def heap_up(index) #index of array, key/val, look at key
+    parent = (index - 1)/2
+
+    while index != 0 && @store[parent].key > @store[index].key
+      swap(parent, index)
+      index = parent
+      parent = (index - 1)/2
+    end
   end
 
   # This helper method takes an index and 
-  #  moves it up the heap if it's smaller
-  #  than it's parent node.
+  # moves it down the heap, if it's larger than its children.
   def heap_down(index)
-    raise NotImplementedError, "Method not implemented yet..."
+    # raise NotImplementedError, "Method not implemented yet..."
+    # return if @store[index].key < r_child && @store[index].key < l_child # index is already set to 0
+    r_child = 2 * index + 2
+    l_child = 2 * index + 1
+    if !(@store[l_child] == nil && @store[r_child] == nil)
+      if @store[index].key > @store[l_child].key || (@store[r_child] != nil && @store[index].key > @store[r_child].key)
+        if @store[r_child] == nil || @store[l_child].key < @store[r_child].key
+          swap(index, l_child)
+          heap_down(l_child)
+        else
+          swap(index, r_child)
+          heap_down(r_child)
+        end
+      end
+    end
   end
 
   # If you want a swap method... you're welcome
@@ -74,4 +107,24 @@ def swap(index_1, index_2)
     @store[index_1] = @store[index_2]
     @store[index_2] = temp
   end
-end
+end
+
+
+
+################################################
+# IGNORE ME!  (spiraled)
+
+# until ((@store[index].key <=  @store[l_child].key) && (@store[index].key <=  @store[r_child].key) -# while the parent is less than 
+  #   if (@store[l_child].key < @store[index].key) && @store[l_child].key < @store[r_child].key
+  #     swap(index, l_child)
+  #     index = l_child 
+  #     l_child.nil?
+  #   elsif (@store[r_child].key < @store[index].key) && (@store[r_child].key < @store[l_child].key)
+  #     swap(index, r_child)
+  #     index = r_child
+  #     r_child = 2 * index + 2
+  #     r_child.nil?
+  #   else
+  #     return
+  #   end
+  # end

test/heapsort_test.rb

@@ -1,6 +1,6 @@
 require_relative "test_helper"
 
-xdescribe "heapsort" do
+describe "heapsort" do
   it "sorts an empty array" do
     # Arrange 
     list = []

test/min_heap_test.rb

@@ -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