COS226

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Lectures

This table contains links to the lecture slides.

#	DATE	SLIDES	SECTION	STUDY	DEMOS
1	Thursday 9/2	Introduction    Percolation	–		–
2	Tuesday 9/7	Union–Find	1.5	guide	Quick-find Quick-union Weighted quick-union
3	Thursday 9/9	Analysis of Algorithms	1.4	guide	–
4	Tuesday 9/14	Stacks and Queues	1.3	guide	Function-call stack Resizing-array queue
5	Thursday 9/16	Advanced Java	–	guide	–
6	Tuesday 9/21	Elementary Sorts	2.1	guide	Selection sort Insertion sort Binary search
7	Thursday 9/23	Mergesort	2.2	guide	Merging
8	Tuesday 9/28	Quicksort	2.3	guide	2-way partitioning 3-way partitioning Quickselect
9	Thursday 9/30	Priority Queues	2.4	guide	Heap operations
10	Tuesday 10/5	Elementary Symbol Tables    BSTs	3.1 3.2	guide guide	BST operations
11	Thursday 10/7	Geometric Applications of BSTs	–	guide	Line segment intersection K-d trees
12	Tuesday 10/12	Balanced Search Trees	3.3	guide	2–3 trees Red–black BSTs
13	Thursday 10/14	Hash Tables	3.4	guide	Linear probing
14	Tuesday 10/26	Graphs and Digraphs I	4.1 4.2	guide	Directed DFS Directed paths Undirected DFS
15	Thursday 10/28	Graphs and Digraphs II	4.1 4.2	guide	Directed BFS Topological sort
16	Tuesday 11/2	Minimum Spanning Trees	4.3	guide	Kruskal Prim
17	Thursday 11/4	Shortest Paths	4.4	guide	Bellman–Ford Dijkstra
18	Tuesday 11/9	Self-Adjusting Data Structures	–		Splay trees
19	Thursday 11/11	Dynamic Programming	IntroCS	guide	–
20	Tuesday 11/16	String Sorts	5.1	guide	Key-indexed counting
21	Thursday 11/18	Tries	5.2	guide	Tries Ternary search tries
22	Tuesday 11/23	no lecture	–		–
23	Tuesday 11/30	Data Compression	5.5	guide	Huffman LZW
24	Thursday 12/2	Algorithm Design	–	guide	–

Readings. All readings refer to Algorithms, 4th edition by R. Sedgewick and K. Wayne unless otherwise specified.

Study guide. Associated with each lecture is a study guide, which summarizes the most important topics and ideas from the lecture. It also includes optional (and ungraded) exercises.

• C level: requires that you be able to carry out the algorithm mechanically. Similar to many of the Quizzera quizzes.
• B level: requires that you really understand what is going on. The exams will have plenty of these.
• A level: requires deep comprehension, involves clever tricks, covers tangential material (or perhaps even all three).

Advice. In general, slides are intended for the lecture presentations and do not provide thorough descriptions of the material alone; for reference, read the corresponding sections from Algorithms, 4th edition. An effective strategy is to skim the textbook before the lecture, read it thoroughly soon afterwards, and complete the corresponding Quizzera quiz (and perhaps some additional B-level exercises from the study guide).

iClickers. To make the lectures more interactive, we will be using iClickers. You must register your remote or mobile/web app to to receive participation credit.

• Hardware remote: register your iClicker remote in Canvas.

• iOS, Android, or web app: Sign up for an iClicker Student account; select Princeton University as the institution; enter your Princeton email address; and select COS 226, Fall 2021 as the course. As of August 2021, iClicker Student should be free to use for Princeton students.

Using a classmate’s iClicker (or allowing someone else to use your iClicker) during lecture is prohibited. You must attend lecture to earn participation credit.

Errata. Here is a list of known errors in the lecture slides and textbook.