Faiza #21

Faiza1987 · 2019-10-01T05:07:09Z

Heaps Practice

Congratulations! You're submitting your assignment!

Question	Answer
How is a Heap different from a Binary Search Tree?	A bst is sorted (elements < root go to the left and elements > root go to right). A heap is not sorted and just follows the rule that it must be filled from left to right and the smallest element in the tree, if it is a min-heap, must be the root or the largest element must be the root in the case of a max-heap.
Could you build a heap with linked nodes?	Yes, if you use an array as the underlying structure.
Why is adding a node to a heap an O(log n) operation?	Because the heap property must be satisfied so whenever a node is added to a heap, it sorts the heap until it satisfies the heap property again.
Were the `heap_up` & `heap_down` methods useful? Why?	Yes, they resorted the heaps to satisfy the heap property for both min and max heaps when a node was added or removed.

CheezItMan

Overall not bad, but there are small issues. Take a look at my comments and see if they make sense. Let me know any questions you have.

CheezItMan · 2019-10-04T22:40:30Z

lib/min_heap.rb

+    swap(0, @store.length - 1)
+    removed_node = @store.pop
+    heap_down(0)
+    return removed_node.value


Getting a NoMethodError here in the "can sort a 5-element array" test.

CheezItMan · 2019-10-04T22:43:31Z

lib/heap_sort.rb

+def heapsort(list)
+  return list if list.empty? || list.length == 1
+
+  minHeap = MinHeap.new()


Just a note that coding style for minHeap should be min_heap

CheezItMan · 2019-10-04T22:48:30Z

lib/min_heap.rb

+    if @store.empty?
+      return
+    end


You're returning nil if @store.empty? I would instead return @store.empty?

Faiza1987 added 3 commits September 22, 2019 12:21

Added code for min_heap with all tests passing

2e332a7

Added code for heapsort

fdcae0a

Added Space/Time Complexity

18e6577

CheezItMan reviewed Oct 4, 2019

View reviewed changes