Objective: To understand recursion by writing simple recursive solutions.
To start the lab: Download and unzip the file at:
Part A: Complete the recursive searchHelper function in the search method of our OrderedList class
in ordered_linked_list.py. Test it with the listTester.py program.
Raise your hand when done. Demonstrate and explain your code to an instructor or TA.
Part B: Recall that Lecture 7 and Section 6.6 discussed a very “non-intuitive”, but powerful list/array-based
approach to implement a priority queue, call a binary heap. The list/array is used to store a complete binary tree
(a full tree with any additional leaves as far left as possible) with the items being arranges by heap-order
property, i.e., each node is ≤ either of its children. An example of a min heap “viewed” an a complete binary tree
would be:
6
15 10
114 20 50
20
300 125 117
[1]
[2] [3]
[4] [5] [6] [7]
[8] [9] [10]
1 2 3 4 5 6 7 8 9 100
not
used 6 15 10 114 20 20 50 300 125 117
Python List actually used
to store heap items
Recall the General Idea of insert(newItem):
append newItem to the end of the list (easy to do, but violates heap-order property)
restore the heap-order property by repeatedly swapping the newItem with its parent until it percolates up to the
correct spot
Recall the General Idea of delMin():
remember the minimum value so it can be returned later (easy to find - at index 1)
copy the last item in the list to the root, delete it from the right end, decrement size
restore the heap-order property by repeatedly swapping this item with its smallest child until it percolates
down to the correct spot
return the minimum value
Originally, we used iteration (i.e., a loop) to percolate up (see percUp) and percolate down (see percDown) the
tree. Now I want you to complete the recursive percUpRec and recursive percDownRec methods in
binHeap.py. Run this file to test your code.
Raise your hand when done. Demonstrate and explain your code to an instructor or TA.
If you have extra time, work on homework #3!
Data Structures (CS 1520) Lab 5 Name:_________________
Lab
5 -
1
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