Homework 5: Heap Solution

Heap




You are to code a Heap, speci cally a MinHeap, that is backed by an array of contiguous elements. Here is a tree and array representation of the same Heap:

















































A MinHeap is a type of binary tree with two main properties.




Shape Property: The tree must be complete. All levels of the tree must be full except the bottom-most level. If the bottom-most level is not full, it must be lled from left to right.




Order Property: Each node’s data is smaller than the data in its two children. There is no explicit relationship between sibling nodes.










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Homework 5: Heap Due: See Canvas










These properties guarantee that the smallest element in the heap will be at the root of the heap.




Although heaps are usually classi ed as a type of tree, they are commonly implemented using an array due to their completeness. In your implementation, you should leave index 0 empty and begin your heap at index 1. This will make the arithmetic to nd parents and children simpler.




You should implement two constructors for this heap. One initializes the heap to a capacity speci-ed as a constant in MinHeap.java. The other constructor should implement the BuildHeap algorithm that was taught in lecture, which is an algorithm that creates a heap in O(n) time. Simply adding the elements one by one will not receive credit since it would be O(n log(n)) in the worst case; see the javadocs for this constructor for more speci cations.




You may assume that your implementation does not need to handle duplicate elements. That is, the add method will never be passed duplicates and the remove method will never have to deal with the heap having duplicates. To be clear, your implementation would most likely work even if we were to test for duplicates; however, this will help remove ambiguity surrounding grading and testing your implementation.




Unlike your BST homework, you are not required to use recursion in this assignment. Use whatever you nd most intuitive - recursion, iteration, or both. However, regardless of the technique you use, make sure to meet e ciency requirements as discussed in lecture.




Grading




Here is the grading breakdown for the assignment. There are various deductions not listed that are incurred when breaking the rules listed in this PDF and in other various circumstances.




Methods:






constructor / buildHeap
20pts




add
20pts




remove
20pts




getMin
5pts




isEmpty
5pts




clear
5pts




Other:






Checkstyle
10pts




E ciency
15pts




Total:
100pts







JUnits




We have provided a very basic set of tests for your code. These tests do not guarantee the correctness of your code (by any measure), nor do they guarantee you any grade. You may additionally post your own set of tests for others to use on the Georgia Tech GitHub as a gist. Do NOT post your tests on the public GitHub. There will be a link to the Georgia Tech GitHub as well as a list of JUnits other students have posted on the class Piazza.




If you need help on running JUnits, there is a guide, available on Canvas under Files, to help you run JUnits on the command line or in IntelliJ.






















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Homework 5: Heap Due: See Canvas










Collaboration Policy




Every student is expected to read, understand and abide by the Georgia Tech Academic Honor Code.




When working on homework assignments, you may not directly copy code from any source (other than your own past submissions). You are welcome to collaborate with peers and consult external re-sources, but you must personally write all of the code you submit. You must list, at the top of each le in your submission, every student with whom you collaborated and every resource you consulted while completing the assignment.




You may not directly share any les containing assignment code with other students or post your code publicly online. If you wish to store your code online in a personal private repository, you can use Github Enterprise to do this for free.




The only code you may share is JUnit test code on a pinned post on the o cial course Piazza. Use JUnits from other students at your own risk; we do not endorse them. See each assignment’s PDF for more details. If you share JUnits, they must be shared on the site speci ed in the Piazza post, and not anywhere else (including a personal GitHub account).




Violators of the collaboration policy for this course will be turned into the O ce of Student Integrity.




Style and Formatting




It is important that your code is not only functional, but written clearly and with good programming style. Your code will be checked against a style checker. The style checker is provided to you, and is located on Canvas. It can be found under Files, along with instructions on how to use it. A point is deducted for every style error that occurs. If there is a discrepancy between what you wrote in accordance with good style and the style checker, then address your concerns with the Head TA.




Javadocs




Javadoc any helper methods you create in a style similar to the existing javadocs. If a method is overridden or implemented from a superclass or an interface, you may use @Override instead of writing javadocs. Any javadocs you write must be useful and describe the contract, parameters, and return value of the method. Random or useless javadocs added only to appease checkstyle will lose points.




Vulgar/Obscene Language




Any submission that contains profanity, vulgar, or obscene language will receive an automatic zero on the assignment. This policy applies not only to comments/javadocs, but also things like variable names.




Exceptions




When throwing exceptions, you must include a message by passing in a String as a parameter. The message must be useful and tell the user what went wrong. \Error", \BAD THING HAP-PENED", and \fail" are not good messages. The name of the exception itself is not a good message. For example:




Bad: throw new IndexOutOfBoundsException(‘‘Index is out of bounds.’’);




Good: throw new IllegalArgumentException(‘‘Cannot insert null data into data structure.’’);




Generics




If available, use the generic type of the class; do not use the raw type of the class. For example, use new LinkedList<Integer() instead of new LinkedList(). Using the raw type of the class will result in a







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Homework 5: Heap Due: See Canvas










penalty.




Forbidden Statements




You may not use these in your code at any time in CS 1332.




package




System.arraycopy() clone()




assert()




Arrays class Array class Thread class




Collections class




Collection.toArray()




Re ection APIs




Inner or nested classes Lambda Expressions

Method References (using the :: operator to obtain a reference to a method)







If you’re not sure on whether you can use something, and it’s not mentioned here or anywhere else in the homework les, just ask.




Debug print statements are ne, but nothing should be printed when we run your code. We expect clean runs - printing to the console when we’re grading will result in a penalty. If you submit these, we will take o points.




Provided




The following le(s) have been provided to you. There are several, but we’ve noted the ones to edit.




MinHeap.java



This is the class in which you will implement the MinHeap. Feel free to add private helper methods but do not add any new public methods, inner/nested classes, instance variables, or static variables.




MinHeapStudentTest.java



This is the test class that contains a set of tests covering the basic operations on the MinHeap class. It is not intended to be exhaustive and does not guarantee any type of grade. Write your own tests to ensure you cover all edge cases.
















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Homework 5: Heap Due: See Canvas










Deliverables




You must submit all of the following le(s). Make sure all le(s) listed below are in each submission, as only the last submission will be graded. Make sure the lename(s) matches the lename(s) below, and that only the following le(s) are present. The only exception is that Canvas will automatically append a -n depending on the submission number to the le name(s). This is expected and will be handled by the TAs when grading as long as the le name(s) before this add-on matches what is shown below. If you resubmit, be sure only one copy of each le is present in the submission. If there are multiple les, do not zip up the les before submitting; submit them all as separate les.




Once submitted, double check that it has uploaded properly on Canvas. To do this, download your uploaded le(s) to a new folder, copy over the support le(s), recompile, and run. It is your sole respon-sibility to re-test your submission and discover editing oddities, upload issues, etc.




MinHeap.java