Niv

lib/heap_sort.rb

@@ -1,5 +1,3 @@
-
-
 # This method uses a heap to sort an array.
 # Time Complexity:  ?
 # Space Complexity: ?

lib/min_heap.rb

@@ -1,6 +1,6 @@
 class HeapNode
   attr_reader :key, :value
-
+  # compare by key, priority field
   def initialize(key, value)
     @key = key
     @value = value
@@ -17,16 +17,25 @@ def initialize
   # Time Complexity: ?
   # Space Complexity: ?
   def add(key, value = key)
-    raise NotImplementedError, "Method not implemented yet..."
+    new_node = HeapNode.new(key, value)
+    new_node_index = @store.length
+    @store.push(new_node)
+    heap_up(@store.length - 1)
+
+    return new_node
   end
 
   # This method removes and returns an element from the heap
   #   maintaining the heap structure
   # Time Complexity: ?
   # Space Complexity: ?
   def remove()
-    raise NotImplementedError, "Method not implemented yet..."
-  end
+    removed = @store[0].value
+    swap(0, @store.length - 1)
+    @store.pop
+    heap_down(0)
+    return removed
+  end 
 
 
   # Used for Testing
@@ -52,20 +61,48 @@ def empty?
 
   private
 
+  def find_parent(index)
+    parent_index = (index - 1)/2
+    return parent_index
+  end
+
   # 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)
-
+    puts to_s
+    parent_index = find_parent(index)
+    if @store[parent_index].key <= @store[index].key || index == 0
+      return
+    end 
+    if @store[parent_index].key > @store[index].key
+      # puts  @store[index].value
+      swap(parent_index, index)
+      index = parent_index
+      heap_up(index)
+    end
   end
 
   # 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..."
+    puts 'heap down'
+    puts to_s
+    child_index = 2*index + 1
+    if index >= @store.length - 1 || child_index >= @store.length - 1
+      return
+    end
+    if @store[child_index].key >= @store[index].key
+      return
+    end 
+    if @store[child_index].key < @store[index].key
+      swap(child_index, index)
+      index = child_index
+      heap_down(index)
+    end
   end
 
   # If you want a swap method... you're welcome