Charlotte - Space #24

charlottea13 · 2020-10-04T00:32:56Z

Heaps Practice

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Question	Answer
How is a Heap different from a Binary Search Tree?	A heap guarantees that elements on higher levels are greater (max-heap) or smaller (min-heap) than elements on lower levels. A binary search tree guarantees order from left-to-right.
Could you build a heap with linked nodes?	Yes, but you should use an array.
Why is adding a node to a heap an O(log n) operation?	Elements are always added to the leaves and you traverse only one side.
Were the `heap_up` & `heap_down` methods useful? Why?	Yes. It's best practice that when you perform an action over and over - you should have a helper method. Helper methods keep the code tidy and more readable.

CheezItMan

Nice work Charlotte, you hit the learning goals here. Well done.

CheezItMan · 2020-10-07T17:39:39Z

lib/heap_sort.rb

+# Time Complexity: O(n)
+# Space Complexity: O(n)

+def heapsort(list)


👍 Adding an element to a heap takes O(log n) time and you're doing it n times... so the time complexity is O(n log n)

CheezItMan · 2020-10-07T17:39:52Z

lib/min_heap.rb

+  # Time Complexity: O(log n)
+  # Space Complexity: O(log n)
  def add(key, value = key)


CheezItMan · 2020-10-07T17:40:05Z

lib/min_heap.rb

+  # Time Complexity: O(log n)
+  # Space Complexity: O(log n)
  def remove()


CheezItMan · 2020-10-07T17:40:18Z

lib/min_heap.rb

+  # Time complexity: O(log n)
+  # Space complexity: O(log n)
  def heap_up(index)


CheezItMan · 2020-10-07T17:40:27Z

lib/min_heap.rb

+  # Helper method takes an index and 
+  #  moves it up the heap if less than parent.
  def heap_down(index)


all tests passing

8fac201

CheezItMan reviewed Oct 7, 2020

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