Computer Science 226
Algorithms and Data Structures
Spring 2014

Course Information | Lectures | Flipped | Assignments | Exercises | Exams


As an alternative to traditional lectures, we are offering a flipped lecture option, in which you watch videos lectures online before class and solve problems in class. Below are the links to flipped activities.

1 2/5 Union Find watchreaddoclasswork
2 - Analysis of Algorithms watchreaddoclasswork
3 2/12 Stacks and Queues watchreaddoclasswork
4 - Elementary Sorts watchreaddoclasswork
5 2/19 MergeSort watchreaddoclasswork
6 - Quicksort watchreaddoclasswork
7 2/26 Priority Queues watchreaddoclasswork
8 - Elementary Symbol Tables · BSTs watchreaddoclasswork
9 3/5 Balanced Search Trees watchreaddoclasswork
10 - Hash Tables, Searching Applications watchreaddoclasswork
11 3/12 Geometric Applications watchreaddoclasswork
12 - Midterm Exam watchreaddoclasswork
13 3/26 Undirected Graphs watchreaddoclasswork
14 - Directed Graphs watchreaddoclasswork
15 4/2 Minimum Spanning Trees watchreaddoclasswork
16 - Shortest Paths watchreaddoclasswork
17 4/9 Maximum Flow watchreaddoclasswork
18 - String Sorts watchreaddoclasswork
19 4/16 Tries watchreaddoclasswork
20 - Data Compression watchreaddoclasswork
21 4/23 Substring Search watchreaddoclasswork
22 - Regular Expressions watchreaddoclasswork
23 4/30 Reductions watchreaddoclasswork
videos and worksheets below have not yet been updated for Spring 2014
24 - TBA watchreaddoclasswork

Flipped lecture students are expected to complete the following activities prior to the flipped lecture:

You need to interact with the video as you watch by inserting comments and/or responding to instructor prompts. This is an important part of your flip experience.

Access flipped lecture videos here

The flipped lecture will be held on Wednesdays 11-12:20pm in Frist 307. We will shape each lecture based on your feedback, using the following structure: Flipped students attend the same precepts, do the same programming assignments, and take the same exams as students attending traditional lectures. The primary difference is that instead of sitting through two 80-minute traditional lectures per week, you will learn as much as possible from online resources (with staff guidance) and attend one 80-minute flipped lecture per week. The flipped lecture will be conducted in a highly interactive, collaborative, and engaging environment.

Why flipped lectures?   We have a rich collection of MOOC (Massive Open Online Course) videos and other supplemental material that is readily available for students in COS 226. The traditional lectures given to a large group of students is often difficult to maintain as interactive sessions. A major portion of a traditional lecture is spent on delivering facts. In a flipped classroom, we deliver factual information through videos. We dedicate the class time to discuss more conceptual questions. Research conducted by Eric Mazur at Harvard found that almost 40% of the students who pass a traditional course do not have the skills to apply knowledge to problems that are unfamiliar. On the other hand, students who focus more on conceptual understanding perform better in long term problem-solving exercises. Here is an interesting video to watch to understand this more. The video is long. You can start from 35:00 and watch about 20-30 minutes to understand how flipped instructions can be beneficial.

To apply.   Before applying for the flipped lecture, think carefully about your style of learning. You may be a good candidate for the flipped lecture if you

If interested, complete this application by 4pm on Monday, February 3. We will announce results by tuesday. Enrollment in the flipped lecture is limited to 28 students.

Lecture videos. You will use the video and document annotation platform FLIP to access the lecture videos. Each lecture video is divided into several segments, of approximately 10 minutes each. To gain access to the FLIP platform, email Guna ( To access the lecture videos from a non-Princeton network, use Secure Remote Access.

In-video instructor prompts. We will have at least one instructor prompt per video. This will be the first comment you will see as you open the video. Please follow the directions given at the beginning of the video. A typical video prompt will also include a link to questions you can respond to after watching the video.

Video annotations. You will use FLIP to add comments to the lecture videos and use tags to categorize them. This is an important part of your flipped learning experience. The comments you make will help you reflect on the video as well as inform us how we should conduct the flipped session when we meet. You need to make at least 3 comments using some of the pre-defined tags. Here is a list of the most common tags:

You may use the same tag more than once. Alternatively, you can summarize what you learned from the video as a good thoughtful comment. Do not make, your comments private. We need to be able to see what comments you make. However, you can make private comments just for you. The following video demonstrates how this works:

More videos may follow

Social annotations. We learn best by observing what others do and do not do. On Tuesday we will open up all comments made by others. Read the comments from others and star at least 3 comments that either you find important or you would like to be discussed in class. You may also reply to others comments. The following video demonstrates how this works:

More videos may follow