An actual tree
CMSC 420 - 0201
Data Structures
Fall 2020
Dave Mount


This course presents fundamental data structures, the algorithms for building and maintaining them, and the mathematical methods for analyzing their efficiencies. Applications in areas such as information retrieval, text processing, operating systems, and geographic information systems will also be discussed. Course material will be reinforced through mathematically-oriented homework problems and programming assignments.


Minimum grade of C- in CMSC351 and CMSC330.

Students are expected to have solid programming skills in Java and a familiarity with the basic concepts from algorithms (e.g., asymptotics, sorting and searching, basic graph algorithms). If you find that you are unfamiliar with any topics that are discussed, please check with the instructor.

Course Work

Course work will consist of a combination of short written homework assignments and a number of programming assignments that cascade into a major programming project. There will be a midterm and a comprehensive final. All course work, including exams, will be submitted remotely and asynchronously, and so there is no requirement to come to campus or to participate at any particular time of the day. Here is a tentative plan for the assigned work, but please note that this is subject to change:

All homework and programming assignments are to be done individually, but discussions with classmates are allowed and encouraged.

Default Late Policy

Unless otherwise noted, the following late policy shall be applied to all course work (written homework assignments and programming assignments).

Online exams must be submitted by the deadline. Late exam submissions will receive zero points.


We will be using Piazza for class discussions. Rather than sending email to the instructor or TA, you are encouraged to post your questions to Piazza, which will allow everyone (instructor, TA, and classmates) to view and respond to your question and the answers posted. (If you have a question of a more private nature, you can send email directly to us.) We will be sending out invitations to the class to join Piazza, but feel free to enroll in the class at any time by going to


The following is very tentative, and the order of topics may be changed.

  • Introduction and Review: Review of basic data structures, algorithms, and analysis.
  • Basic Data Structures: Lists, arrays, trees, graphs: representations and traversals.
  • Ordered Dictionaries and Search Trees: Binary search trees, AVL trees, splay trees, skip lists, treaps, B-trees and variants, optimal binary search trees, digital search trees and Patricia trees, amortized and randomized analyses.
  • Unordered Dictionaries: Hashing functions, chaining, open addressing, linear hashing.
  • Priority Queues: Binary and leftist heaps.
  • Disjoint sets and Partitions: Union-Find, path compression, amortized analysis.
  • Storage allocation: Dynamic storage allocation, buddy system, and garbage collection.
  • Geometric Data Structures: Geometric preliminaries, grid files, and kd-trees (nearest neighbor and range queries), PM-quadtrees, segment and interval trees, range trees, R-trees.

Text and Resources

There is no required text. The books below are suggested reference material. Of course, there is lots of information on the Web.

Lecture Videos

Screen and audio-capture of every lecture will made available via Panopto on ELMS. Videos should be released within 24 hours of each lecture. If a video does not appear, please let me know.

Excused Absences

Any student who needs to be excused for an absence from a single lecture or lab due to illness shall:

Missing an exam for reasons such as illness, religious observance, participation in required university activities, or family or personal emergency (such as a serious automobile accident or close relative's funeral) will be excused so long as the absence is requested in writing at least 2 days in advance of the exam date and the student includes documentation that shows the absence qualifies as excused. A self-signed note is not sufficient, as exams are major scheduled grading events.

For medical absences, you must furnish documentation from the health care professional who treated you. This documentation must verify dates of treatment and indicate the time-frame that the student was unable to meet academic responsibilities. In addition, it must contain the name and phone number of the medical service provider to be used if verification is needed. No diagnostic information will ever be requested. Note that simply being seen by a health care professional does not constitute an excused absence; it must be clear that you were unable to perform your academic duties.

It is the University's policy to provide accommodations for students with religious observances conflicting with exams, but it is the your responsibility to inform the instructor in advance of intended religious observances. If you have a conflict with one of the planned exams, you must inform the instructor prior to the end of the first two weeks of the class.

For missed exams due to excused absences, the instructor will arrange a makeup exam. If you might miss an exam for any other reason other than those above, you must contact the instructor in advance to discuss the circumstances. We are not obligated to offer a substitute assignment or to provide a makeup exam unless the failure to perform was due to an excused absence.

The policies for excused absences do not apply to project assignments. Projects will be assigned with sufficient time to be completed by students who have a reasonable understanding of the necessary material and begin promptly. In cases of extremely serious documented illness of lengthy duration or other protracted, severe emergency situations, the instructor may consider extensions on project assignments, depending upon the specific circumstances.

Besides the policies in this syllabus, the University's policies apply during the semester. Various policies that may be relevant appear in the Undergraduate Catalog.

If you experience difficulty during the semester keeping up with the academic demands of your courses, you may consider contacting the Learning Assistance Service. Their educational counselors can help with time management issues, reading, note-taking, and exam preparation skills.

Students with Disabilities

Students with disabilities who have been certified by University's Accessibility & Disability Service as needing any type of special accommodations should see the instructor as soon as possible during the schedule adjustment period (the first two weeks of class). Please provide ADS's letter of accommodation to the instructor at that time.

All arrangements for exam accommodations as a result of disability must be made and arranged with the instructor at least three business days prior to the exam date; later requests (including retroactive ones) will be refused.

UMD Policies for Undergraduate Students

Please refer to the University's guide on Course Related Policies, which provides you with resources and information relevant to your participation in a UMD course.

Academic Integrity

The Campus Senate has adopted a policy asking students to include the following statement on each examination or assignment in every course: "I pledge on my honor that I have not given or received any unauthorized assistance on this examination (or assignment)." Consequently, you will be requested to include this pledge on each exam and assignment. Please also carefully read the Office of Information Technology's policy regarding acceptable use of computer accounts.

Assignments and projects are to be completed individually. Therefore, cooperation with others or use of unauthorized materials on assignment or projects is a violation of the University's Code of Academic Integrity. Both the person receiving assistance and the person providing assistance are in violation of the honor code. Any evidence of this, or of unacceptable use of computer accounts, use of unauthorized materials or cooperation on exams or quizzes, or other possible violations of the Honor Code, will be submitted to the Student Honor Council, which could result in an XF for the course, suspension, or expulsion.

Violations of the Code of Academic Integrity may include, but are not limited to:

If you have any question about a particular situation or source then consult with the instructors in advance. Should you have difficulty with a programming assignment you should see the instructional staff in office hours, and not solicit help from anyone else in violation of these rules.

It is the responsibility, under the honor policy, of anyone who suspects an incident of academic dishonesty has occurred to report it to their instructor, or directly to the Honor Council.

Every semester the department has discovered a number of students attempting to cheat on assignments, in violation of academic integrity requirements. Students' academic careers have been significantly affected by a decision to cheat. Think about whether you want to join them before contemplating cheating, or before helping a friend to cheat.

You may not share, discuss, or compare assignment solutions even after they have been graded since later assignments may build upon earlier solutions.

Right to Change Information

Although every effort has been made to be complete and accurate, unforeseen circumstances arising during the semester could require the adjustment of any material given here. Consequently, given due notice to students, the instructors reserve the right to change any information on this syllabus or in other course materials. Such changes will be announced and prominently displayed at the top of the syllabus.

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