Magic List
Goal
The goal of this assignment is to get some practice with data structure implementation and usage in
python. In Part (a) of the assignment you have to complete some functions of the Magic List data
structure. In Part (b) of the assignment you have to use a Magic List to solve the given problem.
Part (a) - Magic List
Magic List is a special type of list L in which the elements are arranged according to the following
properties :
1. The first element of the list is always 0 (L[0] = 0).
2. For each index i (>= 1), L[i] <= L[2i] and L[i] <= L[2i+1].
3. For each index i (>= 1), L[i/2] is called the parent of L[i], and L[2i], L[2i+1] are called the children of
L[i].
4. L[1] has no parent.
In this list, all the elements besides the first one are called magic elements. The size of Magic List is
the number of magic elements in the list. Observe that L[1] will be the smallest magic element in list
(Due to point 2. above).
A class called MagicList has been given to you (inside MagicList.py). You have to complete the
following functions inside the file :
1. findMin
Complete the findMin function and return the smallest magic element in the Magic List. If there are
no magic elements (i.e. size of Magic List is zero), then return None.
2. insert
Complete the insert function and return the modified list. To insert an element in the Magic List, first
append the element to the end of the list. Start at last element and keep comparing with parent
L[i/2]. If parent is larger, swap the parent and the element. Keep doing this till parent is smaller, or
the element has no parent.
3. deleteMin
Complete the deleteMin function, delete the smallest magic element in the Magic List, and return
the modified list. To delete the minimum element, swap the minimum element (E1) with the last
element (E2) and remove the last element. Keep comparing E2 with children L[2i] and L[2i+1] and
swap with the smaller child. Keep doing this till both children are greater than E2 or E2 has no more
children.
Part (b) - k-sum
In this part, you have to complete the function k-sum. The function takes a list L and an integer K as
input, and you need to find the sum of smallest K elements of the list. You need to do this with the
help of a Magic List.
To convert the input list L into a Magic list, you can start with an empty MagicList M and insert all
the elements of L into M (Code given below). Then use M to find the sum of smallest K elements and
return the sum. Note that K <= size of L
1. # Convert a list L to Magic List M
2. M = MagicList ()
3. for i in L :
4. M. insert ( i )
5. # M now contains all elements of L
Testing
The given code contains a few test cases for each function. You need to ensure that each test case
passes correctly. Do not change anything in the code except completing the given functions.
Submission
You need to submit completed MagicList.py on moodle. Grading would be done on the basis of a
demo (viva). You should be able to run your code using python3 during the demo.
What is allowed? What is not?
1. This is an individual assignment. 2. Your code must be your own. You are not to take guidance
from any general purpose code or problem specific code meant to solve these or related problems.
3. We will run plagiarism detection software. Anyone found guilty will be awarded a suitable penalty
as per IIT rules.

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