Alex #11

alexandria7 · 2019-09-27T05:29:19Z

Heaps Practice

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Question	Answer
How is a Heap different from a Binary Search Tree?	A heap has less strict rules than a binary search tree. While a BST requires that every child to the left of a node must be less than the node and every child to the right of the node must be greater than the node, a heap requires that all children must be greater than the parent (min heap) or smaller than the parent (max heap).
Could you build a heap with linked nodes?	Yes you could, but using an array is preferable since it helps to use an index to look up each value.
Why is adding a node to a heap an O(log n) operation?	Because the heap has O(logn) levels and we only have to hit each level once.
Were the `heap_up` & `heap_down` methods useful? Why?	Yes! These helper methods made adding and removing nodes from a heap much cleaner.

CheezItMan

Nice work. You hit the learning goals here. Well done!

CheezItMan · 2019-10-04T21:13:09Z

lib/heap_sort.rb

CheezItMan · 2019-10-04T21:14:02Z

lib/min_heap.rb

-  # Time Complexity: ?
-  # Space Complexity: ?
+  # Time Complexity: O(logn) where n is the length of the @store
+  # Space Complexity: O(1)


Since your heap_down method is recursive you have O(log n) being saved on the call stack.

CheezItMan · 2019-10-04T21:23:33Z

lib/min_heap.rb

-  # Time Complexity: ?
-  # Space Complexity: ?
+  # Time Complexity: O(logn) where n is the length of the @store
+  # Space Complexity: O(1)


alexandria7 added 3 commits September 19, 2019 15:35

wrote add and heap_up methods so tests pass

e6cee6a

wrote methods to make tests pass

b2a8920

made heap_up recursive

c781d67

CheezItMan reviewed Oct 4, 2019

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