Welcome to CSE 123: Introduction to Computer Programming III 🎉

What is this class? What will I learn?

Computing continues to play an ever-increasing role in today’s society. Having an understanding of computing is an essential skill for those in the 21st century; from working in industries more reliant on technology, using computational methods to further scientific understanding, or being an informed citizen in a world with technology all around us.

This course is a third course in computer programming focused on the design and implementation of data structures. It assumes students already have significant experience with programming and understand fundamental computing concepts (such as control structures (loops and conditionals), variables and data, and arrays) as well as basic data structure (lists, sets, stacks, queues, and maps/dictionaries) and the fundamentals of object-oriented programming.

In this course, students will learn:

  1. How to implement compound data structures such as lists and trees.
  2. The use of recursion to efficiently solve computational problems.
  3. How to utilize inheritance to represent relationships among similar classes.
Prior Experience and Expectations

Prerequisite Material

This course is intended for students who already have some programming experience. Students entering CSE 123 should already be familiar with programming constructs for problem decomposition (methods or functions), control structures (loops and conditionals), variables and data types (such as integer data), data structures such as arrays, lists, sets, and maps/dictionaries, and the basics of object-oriented programming.

To better assess if CSE 123 is the right class for you, the Allen School has developed a Self-Guided Placement to help students assess which intro course is the right one for them to enroll in. Please see this website for more information on who to contact if you have questions about which introductory CSE course is the right course for you.

Programming Language

CSE 123 is taught in the Java programming language. Unlike CSE 122, CSE 123 does assume prior experience with the Java programming langauge. If you have not programmed in Java before, or if you would like to get some extra practice or review, please see our Java Tutorial.


If you want to learn more about the course and its policies, please check out our course syllabus.


Feedback is always welcome! You can contact the the course staff or submit anonymous feedback.


Please do not email the course staff or instructors regarding registration for the course. The course staff do not have access to add codes. Please email ugrad-adviser@cs.washington.edu for assistance.


This Week (at a glance)

Monday (12/04)

  • 📚 Pre-Class Material 17 (Complete before class.)
  • 👥 Lesson 17: Hashing
    Class sessions @ 12:30 in KNE 120 and 2:30 in SAV 260.

Tuesday (12/05)

  • 🧑‍🏫 Section 17: Review

Wednesday (12/06)

  • 📚 Pre-Class Material 18 (Complete before class.)
  • 👥 Lesson 18: Victory lap and next steps
    Class sessions @ 12:30 in KNE 120 and 2:30 in SAV 260.
  • 💻 P3 - Huffman due @ 11:59 pm.

Thursday (12/07)

  • 🧑‍🏫 Section 18: Review

Friday (12/08)

  • Nothing!

Saturday (12/09)

  • Nothing!

Sunday (12/10)

  • Nothing!



This is a rough sketch of the quarter and things are subject to change. We can accurately predict the past, but predicting the future is hard!


Anything listed in the “Lesson” materials for a day should be read before attending class that day. The Lessons are a first introduction to the most important terms and concepts for that day of class. It is okay if the Lesson doesn’t make complete sense as we have the rest of the class day to clarify the concepts, but if you don’t do the Lesson the class session won’t make any sense.

Topic Programming / Creative Projects Resubmissions
Week 0
Mon 09/25
HOLIDAY No class
Tue 09/26
HOLIDAY No class
Wed 09/27
LES 00 Welcome; Syllabus Details

Note: Normally you would complete the Pre-class Work before class. There is nothing you need to complete before class today!

in-class: pdf pptx
Extra resources
Thu 09/28
SEC 00 Welcome
Warm Up/Review
I.S. by 11:59 pm
Fri 09/29
Week 1
Mon 10/02
LES 01 Implementing data structures; References
Tue 10/03
SEC 01 Implementing data structures; References
Wed 10/04
LES 02 Pre-/Post-conditions; Exceptions
Abstract Strategy Games
I.S. by 11:59 pm
Thu 10/05
SEC 02 Pre-/Post-conditions; Exceptions
Fri 10/06
Week 2
Mon 10/09
LES 03 Inheritance; Polymorphism
Tue 10/10
SEC 03 Inheritance; Polymorphism
Wed 10/11
LES 04 Abstract classes; Comparable
Survivor Challenge
I.S. by 11:59 pm
Resub 0
Due 11:59 pm
Thu 10/12
SEC 04 Abstract classes; Comparable
Fri 10/13
Week 3
Mon 10/16
LES 05 Linked nodes
Resub 1
Due 11:59 pm
Tue 10/17
QUIZ 00 Quiz 0

Note: Information for Quiz 0

  • Topics on Quiz: Inheritance, Polymorphism, Abstract classes, Comparable
  • Topics not on Quiz: Linked nodes

Wed 10/18
LES 06 Linked nodes w/loops
Thu 10/19
SEC 06 Linked nodes
Fri 10/20
Week 4
Mon 10/23
LES 07 Linked lists
Resub 2
Due 11:59 pm
Tue 10/24
SEC 07 Linked nodes w/loops
Wed 10/25
LES 08 Putting it all together
I.S. by 11:59 pm
Thu 10/26
SEC 08 Linked lists
Fri 10/27
Week 5
Mon 10/30
LES 09 Recursive tracing
Resub 3
Due 11:59 pm
Tue 10/31
QUIZ 01 Quiz 1

Note: Information for Quiz 1

  • Topics on Quiz: Linked nodes, Linked lists
  • Topics not on Quiz: Recursion

Wed 11/01
LES 10 Recursive programming
Mondrian Art
I.S. by 11:59 pm
Thu 11/02
SEC 10 Recursive tracing; Recursive programming
Fri 11/03
Week 6
Mon 11/06
LES 11 Exhaustive search
Resub 4
Due 11:59 pm
Tue 11/07
SEC 11 Exhaustive search
Wed 11/08
LES 12 Recursive backtracking
Disaster Relief
I.S. by 11:59 pm
Thu 11/09
SEC 12 Recursive backtracking
Fri 11/10
Week 7
Mon 11/13
LES 13 Binary trees
Resub 5
Due 11:59 pm
Tue 11/14
SEC 13 Binary trees intro
Wed 11/15
LES 14 Binary search trees; x = change(x)
"BrettFeed" Quiz
I.S. by 11:59 pm
Thu 11/16
SEC 14 Binary tree modification
Fri 11/17
Week 8
Mon 11/20
HOLIDAY [Optional] Fun other stuff in CS. (Lecture A only, 12:30. No B lecture)
Resub 6
Due 11:59 pm
Tue 11/21
HOLIDAY No class
Wed 11/22
HOLIDAY No class
Thu 11/23
HOLIDAY Thanksgiving
Fri 11/24
HOLIDAY Native American Heritage Day
Week 9
Mon 11/27
LES 15 Runtime analysis
Resub 7
Due 11:59 pm
Tue 11/28
QUIZ 02 Quiz 2

Note: Information for Quiz 2

  • Topics on Quiz: Recursion, Recursive backtracking, Binary trees

Wed 11/29
LES 16 Huffman encoding

Note: These slides are from a previous course but are still applicable to CSE 123 this quarter.

in-class: slides
I.S. by 11:59 pm
Thu 11/30
SEC 16 Runtime analysis; Huffman encoding
Fri 12/01
Week 10
Mon 12/04
LES 17 Hashing
Resub 8
Due 11:59 pm
Tue 12/05
SEC 17 Review
Wed 12/06
LES 18 Victory lap and next steps
in-class: pdf pptx
Thu 12/07
SEC 18 Review
Fri 12/08
Week 11
Mon 12/11
EXAM Final exam review session - 4:30-6:30pm (SMI 120)
Resub 9
Due 11:59 pm
Tue 12/12
EXAM Final Exam - 12:30-2:20pm (KNE 130)
Wed 12/13
Thu 12/14