COS226

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Lectures

This table contains links to the lecture slides.

#	DATE	SLIDES	SECTION	STUDY	DEMOS
1	Tuesday 1/31	Introduction    Union–Find	1.5	guide	Quick-union Weighted quick-union
2	Thursday 2/2	Analysis of Algorithms	1.4	guide	–
3	Tuesday 2/7	Stacks and Queues	1.3	guide	Function-call stack Resizing-array queue
4	Thursday 2/9	Advanced Java	–	guide	–
5	Tuesday 2/14	Elementary Sorts	2.1	guide	Selection sort Insertion sort Binary search
6	Thursday 2/16	Mergesort	2.2	guide	Merging
7	Tuesday 2/21	Quicksort	2.3	guide	2-way partitioning 3-way partitioning Quickselect
8	Thursday 2/23	Priority Queues	2.4	guide	Heap operations
9	Tuesday 2/28	Elementary Symbol Tables    BSTs	3.1 3.2	guide guide	BST operations
10	Thursday 3/2	Balanced Search Trees	3.3	guide	2–3 trees Red–black BSTs
11	Tuesday 3/7	Midterm Review	–		–
12	Thursday 3/9	Midterm	–		–
13	Tuesday 3/21	Geometric Applications of BSTs	–	guide	Line segment intersection K-d trees
14	Thursday 3/23	Hash Tables	3.4	guide	Linear probing
15	Tuesday 3/28	Graphs and Digraphs I	4.1 4.2	guide	Directed DFS Directed paths Undirected DFS
16	Thursday 3/30	Graphs and Digraphs II	4.1 4.2	guide	Directed BFS Topological sort
17	Tuesday 4/4	Minimum Spanning Trees	4.3	guide	Kruskal Prim
18	Thursday 4/6	Shortest Paths	4.4	guide	Bellman–Ford Dijkstra
19	Tuesday 4/11	Dynamic Programming	IntroCS	guide	–
20	Thursday 4/13	Maxflows and Mincuts	6.4	guide	Ford–Fulkerson
21	Tuesday 4/18	String Sorts	5.1	guide	Key-indexed counting
22	Thursday 4/20	Tries	5.2	guide	Tries Ternary search tries
23	Tuesday 4/25	Data Compression	5.5	guide	Huffman LZW
24	Thursday 4/27	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. To earn participation credit, you must attend lecture and participate in the iClicker polls. You must also register your mobile/web app:

• If needed, create a iClicker Student account.

  • Select Princeton University as the institution.

  • Enter your name, Princeton email address, and NetID.

• Select COS 226, Spring 2023 for the course.

Using a classmate’s iClicker (or allowing someone else to use your iClicker) during lecture is prohibited.

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