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[katemyer]

Heaps Practice

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Comprehension Questions

Question	Answer
How is a Heap different from a Binary Search Tree?	Heaps guarantee that the elements on higher levels are greater for max heaps or lower for min heaps. But, the BST guarantees that there is order from left to right, this is useful for searching elements that are sorted.
Could you build a heap with linked nodes?	No because heaps are binary trees. You can store the heap into an array since it's easier to manage memory.
Why is adding a node to a heap an O(log n) operation?	Because the smallest possible height for a heap with N nodes is o log n.
Were the heap_up & heap_down methods useful? Why?	Heap up methods are useful in adding elements to a heap, by comparing the new node to its parent and swapping them if they are out of order, and updating a lcoation. The heap down is useful to remove an element by swapping the last leaf with the root and done until there are more swaps left.

[CheezItMan]

Not bad Kate, one minor note on heal_down, and some notes on space/time complexity due to recursion. Otherwise well done.

[CheezItMan]

👍

[CheezItMan]

👍 However since you are doing recursion the space complexity is O(log n) due to the call stack.

[CheezItMan]

👍 However since you are doing recursion the space complexity is O(log n) due to the call stack.

[CheezItMan]

What if the left child index is less than the length and the value at the left child index is less than the current parent!

Suggested change

	elsif right_child_index >= @store.length
	return
	end
	elsif right_child_index >= @store.length && @store[left_child_index].key >= @store[index].key
	return
	end