Water - Mackenzie

lib/heap_sort.rb

@@ -1,8 +1,23 @@
 
 
 # This method uses a heap to sort an array.
-# Time Complexity:  ?
-# Space Complexity: ?
+# Time Complexity:  O(m+n) 
+# Space Complexity: O(n) - will have a call stack equal to number of nodes, though we are make a constant number of data structures... maybe O(1)
 def heap_sort(list)
-  raise NotImplementedError, "Method not implemented yet..."
-end
+  # raise NotImplementedError, "Method not implemented yet..."
+  # left_child = i * 2 + 1 
+  # right_child = i * 2 + 2
+  heap = MinHeap.new
+
+  list.each do |element|
+    heap.add(element)
+  end
+
+  sorted_list = []
+  until heap.empty?
+    sorted_list.push(heap.remove)
+  end
+
+  return sorted_list
+
+end 

lib/min_heap.rb

@@ -14,18 +14,26 @@ def initialize
   end
 
   # This method adds a HeapNode instance to the heap
-  # Time Complexity: ?
-  # Space Complexity: ?
+  # Time Complexity: O(m+1), where m is height  -  O(1) for adding, O(m) for heap up
+  # Space Complexity: O(1) -  no new data structures made, but O(m) for heap up call stack (is it the number of calls in the calls stack or number of structures made?)
   def add(key, value = key)
-    raise NotImplementedError, "Method not implemented yet..."
+    @store << HeapNode.new(key, value)
+
+    if @store.length > 1
+      heap_up(@store.length - 1)
+    end
+
   end
 
   # This method removes and returns an element from the heap
   #   maintaining the heap structure
-  # Time Complexity: ?
-  # Space Complexity: ?
+  # Time Complexity: O(n+1)
+  # Space Complexity: O(1)
   def remove()
-    raise NotImplementedError, "Method not implemented yet..."
+    swap(0, -1)
+    popped = @store.pop 
+    heap_down(0)
+    return popped.value
   end
 
 
@@ -44,31 +52,61 @@ 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..."
+
+    if @store.nil? || @store.length == 0
+      return true
+    else 
+      return false
+    end
+
   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: ?
+  # Time complexity: O(m) where m is height
+  # Space complexity: O(1), no persistent data structure is made beyond 1 temporary reassigned variable
   def heap_up(index)
+    return if index == 0
+
+    if @store[index].key < @store[((index - (index % 3)) / 2)].key 
+      temp = @store[index] 
+      @store[index] = @store[((index - (index % 3)) / 2)]
+      @store[((index - (index % 3)) / 2)] = temp
+    end
+
+    heap_up(((index - (index % 3)) / 2))
 
   end
 
   # This helper method takes an index and 
   #  moves it up the heap if it's smaller
   #  than it's parent node.
+  # left_child = i * 2 + 1 
+  # right_child = i * 2 + 2
   def heap_down(index)
-    raise NotImplementedError, "Method not implemented yet..."
+    return if @store[index].nil?
+
+    if !@store[index * 2 + 1].nil? && @store[index].key > @store[index * 2 + 1].key
+      swap(index, (index * 2 + 1))
+    end
+
+    if !@store[index * 2 + 2].nil? && @store[index].key > @store[index * 2 + 2].key
+      swap(index, (index * 2 + 2))
+    end
+
+    heap_down(index * 2 + 1)
+    heap_down(index * 2 + 2)
+
   end
 
   # If you want a swap method... you're welcome
+  #THANK YOUUUUUU
   def swap(index_1, index_2)
     temp = @store[index_1]
     @store[index_1] = @store[index_2]

test/heapsort_test.rb

@@ -1,12 +1,12 @@
 require_relative "test_helper"
 
-xdescribe "heapsort" do
+describe "heapsort" do
   it "sorts an empty array" do
     # Arrange 
     list = []
 
     # Act
-    result = heapsort(list)
+    result = heap_sort(list)
 
     # Assert
     expect(result).must_equal []
@@ -17,7 +17,7 @@
     list = [5]
 
     # Act
-    result = heapsort(list)
+    result = heap_sort(list)
 
     # Assert
     expect(result).must_equal [5]
@@ -28,7 +28,7 @@
     list = [5, 27, 3, 16, -50]
 
     # Act
-    result = heapsort(list)
+    result = heap_sort(list)
 
     # Assert
     expect(result).must_equal [-50, 3, 5, 16, 27]

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"
-  end
+    # Another assert
+    expect(removed).must_equal "Pasta"
+    end
 end