CS2040S - Data Structures and Algorithms

Introduction

This course introduces students to the design and implementation of fundamental data structures and algorithms. The course covers basic data structures (linked lists, stacks, queues, binary heaps, hash tables, trees, and graphs), searching and sorting algorithms, and basic analysis of algorithms.

The programming language used for this course is Java.

We use very basic object-oriented programming concepts in various data structures implementations, e.g., Stack class inherits LinkedList class (more details of OOP are in CS2030).

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Course Registration

Prof Halim is focusing on SoC Computer Science (CS) cohort since S2 AY 2022/23 - present.
That's it, if you take SoC CS, you will either encounter Prof Halim in CS2040S S1 and/or CS3230 S1.
If you reach this page because you are looking for CS2040C information, Prof Halim doesn't teach that version now, contact Prof Alan Cheng.

Some facts:

Prof Halim has implemented flipped classroom (a type of blended learning) techniques, employing machine-teach-(and-auto-test)-students-on-basic-stuffs, along with in-class live discussion of more challenging problems in his CS2040/C/S classes. From AY 2017/18 until the present, he has received teaching feedback ratings from 4.2 (slightly above average) to 4.8 (very good) out of a maximum of 5.0 for these offerings, with a running average rating of 4.455 (very good).
Apart from teaching CS2040/C/S on multiple occassions from 2017 to the present, Prof Halim has also taught similar courses that are variants of the current version of CS2040/C/S, namely CS2020 once (2011), CS2010 six times (2011-2016), CS1020E once (2016), and IT5003 (2020-present).

Teaching staffs:
Associate Professor Steven Halim, the key man behind VisuAlgo, a tool that will be extensively utilized in this course.
The primary goal for this S1 AY2024/25 is for Prof Halim to survive teaching three (large) courses at the same time (CS2040S - 145 pax; IT5003 - 14 pax (surprisingly small); CS3230 - 392 pax; totalling up to 551 pax).
One key way to do that is to align CS2040S as close as possible to its subset course IT5003.

Rating (out of 5.0)	Aug-Nov 24 (n=??/145?) ≥ 50% ??	Aug-Nov 23 (n=90/128) 70% ▼	Aug-Nov 22 (n=162/206) 79% ▲	Jan-May 22 (n=101/131) 77% ▲	Aug-Dec 21 (n=49/69) 71% ▲	Jan-May 21 (n=158/253) 62% ▲	Aug-Dec 20 (n=60/115) 52% ▼
Course feedback (SoC avg lvl 2000 ~3.9)	4.2 (tgt)	4.2 ==	4.2 ==	4.2 == (+Alan)	4.2 ==	4.2 ▲ (+Alan)	3.8 ▼ (C-19+IOI 20)
Course difficulty (SoC avg lvl 2000 ~3.8)	4.1 (tgt)	4.3 ==	4.3 ▲	4.2 == (high)	4.2 ▲	3.9 ▼ (easiest)	4.6 ▲ (C-19+IOI 20)
Prof Halim's teaching (SoC avg lvl 2000 ~4.2)	4.3 (tgt)	4.4 ▼	4.5 ▲	4.3 ▼ (+Alan)	4.5 ▲	4.4 ▲ (+Alan)	4.3 ▼ (C-19+IOI 20)

Update on 17 Jul 2024
Prof Halim has found best 8 TAs for this semester.
For the other 48-8 = 40 not-successful applicants, try again next semester (Sem2 version of CS2040S is much bigger).
Or pivot to CS2040 (with Dr Ket Fah), CS2040C (with Dr Alan/Sanka) or try the new CS2040DE (with Design and Engineering faculty)
Or consider re-applying to CS3230 (I still need 2 other part-time TAs) if you have also cleared CS3230.

Date, Time	Live Session (Venue) (#Stu/#Cap)	No	TA
1/Mon, 1000-1200	COM1-B109 (PL2) (XY/19)	01	@pisciprehender
1/Mon, 1000-1200	COM1-B108 (PL3) (XY/19)	02	@saddle196883
1/Mon, 1200-1400	COM1-B109 (PL2) (XY/19)	03	@chiralcentre
1/Mon, 1200-1400	COM1-B108 (PL3) (XY/19)	04	@ernest__
1/Mon, 1400-1600	COM1-B108 (PL3) (XY/19)	05	@sandyk_sk
1/Mon, 1400-1600	COM1-B111 (PL4) (XY/19)	06	@chronal_02
1/Mon, 1600-1800	COM1-B108 (PL3) (XY/19)	07	@json.c
1/Mon, 1600-1800	COM1-B111 (PL4) (XY/19)	08	@ahzong
5/Fri, (night, TBC)	Zoom Recurring Link TBA (free and easy)	-	TBA
6/Sat, (morning, TBC)	Zoom Recurring Link TBA (free and easy)	-	TBA

List of TAs (ordered using Lab Group Number):

@pisciprehender, Zhang Puyu (peak rating: 4.9/CS1010; also 4.7/CS2030S last S2; also CS1010 TA)
@saddle196883, Timothy Wan Kai Yang (peak rating: 4.8/CS2040S; also planning to do CS1231S TA)
@chiralcentre, Ryan Tan Wei Jie (peak rating: 4.9/CS2040S)
@ernest__, Ernest Ng Zi Xuan (peak rating: 4.6/CS2040S+CS2040C)
@sandyk_sk, Sandy Kristian Waluyo (IMO 22 Bronze, new NUS TA)
@chronal_02, Winston Leonard Prayonggo (peak rating: 4.9/CS2040S last S2; also CS1101S TA)
@json.c, Jason Christopher (peak rating: 5.0/CS2040S; taken again; also CS3264 TA)
@ahzong, Chong Chin Herng (peak rating: 4.9/CS1231S; also 4.6/CS2040S last S2; also CS1231S TA)
Special part-time TA for grading midterm+final only: Ivan Chew Teck Meng
PE Setting Only: Muhammad Ayaz Dzulfikar

Have you passed (or exempted from) CS1010 (or its variants)? You have to...
For CS2040S, have you passed CS1231 (or its variants)? You have to...
Have you taken CS1020/CS1020E/CS2010/CS2020? You cannot take CS2040/C/S if you have taken similar/older course(s) that have huge degree of overlap with this course.

Syllabus

This is what you will learn if you take CS2040/C/S taught by Prof Halim, compare it with the subset IT5003 version:

Part 0: A quick review of CS1101S/CS1010/variants - Programming Methodology
Part 1: Algorithms using the simplest Linear Data Structure:
1. Simple algorithms involving (Resize-able) Array/Java ArrayList (some are Complete Search, a.k.a., Brute Force)
2. Various Sorting algorithms (DnC) and a few simple (Greedy) algorithms that are applicable after sorting the data
Part 2: Various Linear Data Structures (DSes):
1. List Abstract Data Structure (ADT)
2. Stack, Queue, and Deque ADTs in their Linked List implementations
3. Stack and Queue in their (resize-able/circular) Array implementations
Part 3: Various (Non-)Linear Data Structures (DSes):
1. Priority Queue (PQ) ADT, its Binary Heap implementation (DnC), and Greedy algorithm with PQ (Greedy)
2. Disjoint Sets ADT and its Union-Find Disjoint Sets implementation (DnC)
3. Table/Map (ADT) part 1 (unordered) and its Hash Table implementation (DnC)
4. Table/Map (ADT) part 2 (ordered) and its Binary Search Tree (BST) implementation, inclusive of the balanced BST version: Adelson-Velskii Landis (AVL) Tree (DnC)
5. Graph DS: Adjacency Matrix/Adjacency List/Edge List/Implicit Graph
Part 4: Algorithms for Graph Problems:
1. Graph Traversal (BF): Depth-First Search (DFS), Breadth-First Search (BFS), and various application scenarios (Complete Search)
2. Single-Source Shortest Paths (SSSP): Bellman-Ford algorithm (DP), Dijkstra's algorithm (two versions, Greedy), various special cases and various application scenarios, e.g., Shortest Paths on unweighted graph (BFS), DAG (DP), Shortest Paths on Tree
3. Minimum Spanning Tree (MST): Kruskal's or Prim's algorithms (both are Greedy) and its applications
Part 5: Beyond polynomial-time algorithms: Short introduction to the theory of NP-completeness (preview of CS3230)
Throughought this course:
1. More advanced data structures and algorithms design and analysis (compared to Programming Methodology, but not as advanced as CS3230)
2. Various trade-offs situations
3. Real-life problem solving skills (Complete Search/Brute Force/BF, Divide and Conquer/DnC, Greedy, and Dynamic Programming/DP)
4. Recursive thinking
5. Proper implementation (more emphasis) of (some) data structures and algorithms in Java with (lesser emphasis) their Java API version at the end

Course Registration Additional FAQ

If you have any important questions regarding this course, email dcssh at nus edu sg. Relevant answers will be posted here to reach wider audiences.

Q: Will there be a Practical Exam (PE) for your version of CS2040/C/S?

A: Yes, there will be a Practical Exam (PE) held once, specifically on Week 10, covering all topics up to just before the graph data structure. However, due to the availability of generative AI tools like ChatGPT, Prof Halim is no longer feels comfortable conducting an Open Internet PE (and also not allowed to). Instead, the plan is to implement onsite proctoring with some form of Internet firewall. The specific details are yet to be confirmed.

Q: PE sounds scary... Will there be a make up PE if I am sick/underperform...?

A: Yes. Prof Halim is aware that many students are still at learning stage. Those who are absent from the official ones for valid reason (clash with another official NUS course, Medical Certificate (MC), Bereavement of immediate family member, representing NUS for official event) and a few bottom X (TBC) students will be invited for the make up PE sometime during study week.

Q: Will this course be graded using Bell curve?

A: CS2040S has much more than 40 students each semester. Bell curve system will obviously be used.

Q: I am from CS1101S (subset of JavaScript)/CS1010S or CS1010E (Python)/other modules that do not use Java, should I pick up Java on my own during this May-June-July 2024 University Holiday?

A: Yes, that is a very good idea. We will only review basic Java in the first few weeks of this course and then Prof Halim will encourage you to self-learn Java along the way.

Q: What Integrated Development Environment (IDE) that we will use in your version of CS2040/C/S?

A: The choice of IDE is "up to you but", but do check what Java-related IDEs are available in our PLs.

Q: Do I have to buy any textbook for this course?

A: Generally, no. But my CS3233 textbook: Competitive Programming book: CP4, Book 1 (get a copy legally from lulu.com (eBook) or lulu.com (physical, need shipping from overseas)) should be a good book to have. The answers for many of my test questions may be inside that book. The problem is... I discuss over ~3900+ problems in that book, near impossible to solve them all in just one semester.

Q: Can I S/U this course if I am a freshman when I take this course?

A: No, as this is a level-2 core course. CS2040/C/S has CS1010 as pre-requisite and according to Registrar's Office: "The S/U option will apply to all Level 1000 courses (with or without pre-requisites) and Level 2000 courses without other NUS courses as pre-requisites, unless otherwise stipulated by the Faculties/Departments.". So factor this information when taking this course.

Q: I heard from my friend/senior that your version of CS2040/C/S is a flipped classroom course?

A: You heard that correctly. Prof Halim and his FYP students are working hard at the background to continuously improve his 24/7 electronic clone, VisuAlgo, to be able to explain basic data structures and algorithms concepts covered in CS2040/C/S as clear as possible to first timer (and to automatically test students about these basic concepts). This will free the precious 2+1h (effective 95+45m = 140m per week to discuss the harder/deeper part of the syllabus and to do live demonstration of how those data structures and algorithms can be used to solve (real life, but sometimes fictional) programming problem. This will also help Prof Halim to scale himself (one person) to handle much larger algorithm class (CS2040/C/S are projected to be as big as of now (over 1000 students per batch) in future AYs as NUS SoC freshmen intake remains at high level — but Prof Halim feels the student intake number will plateau soon).

Q: What are the potential changes that you will apply to CS2040/C/S in S1 AY 2024/25 compared to your many earlier runs of this course?

A: NUS @ Kattis is still used. Prof Halim only plan to change these variables this time:

From S1 AY24/25, IT5003 (Python) also starts from Week 01. That course only has 2 hours Wednesday night lecture per week instead of 2+1 = 3 hours and will end by Week 12 instead of Week 13. Prof Halim is planning to make the two courses 'as close' as possible to reduce his own workload, i.e., by synchronizing almost all Wed morning (10am-12nn XYa lecture in CS2040S) and Wed evening (6.30-8.30pm XY lecture in IT5003) to be as identical as possible. CS2040S 'extra' topics will always be scheduled on Thu morning (9-10am XYb lecture).
Prof Halim will try to make this course has difficulty rating in [4.0-4.1] range instead of 4.3, 4.3, 4.2, 4.2 in his last four iterations..., i.e., he is conciously making the course a bit easier, closer to IT5003 version
Prof Halim will have to disappear three times: on Week 04 (IOI 2024, Alexandria, Egypt), on Week 06 (ICPC World Finals 2024, Astana, Kazakhstan), and on Week 09 (ICPC Challenge Championship). On all weeks, there will be special substitutes covering for Prof Halim.
Since our Thursday lecture slot is moved from 5-6pm (evening) to 9-10am (morning), Prof Halim decides to halve the duration (and thus the difficulty) of PE. The weightage of 15% PE is now reduced to 11% and the 4% is spread to midterm and the usually easier VisuAlgo Online Quizzes.
All others are planned to be kept roughly constant.

Note: This course registration section will not be prominent from Week 1 onwards. This behavior is normal. You can view it again by scrolling to the top of this page.

News

Date	News

Lesson Plan

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The 4 units CS2040/C/S syllabus will be delivered over 13 weeks.
This course is a superset of the content of a similar IT5003 course, approximately 39/24 ~= 63% more content than IT5003.
The weekly lesson plan of Week X is typically as follows (2+(1+1)+(2+1)+3 = 10 hours/week):

Give yourself about 2-hours/week to self-study as much as you can from various online Java references (especially during the early transition weeks) and VisuAlgo about the designated topic and attempt the e-Lecture/Online Quiz questions first (flipped classroom),
On Tutorial+Lab day, attempt and then actively participate on 1-hour/week (effective 45 minutes) tutorial slot of past week X-1 topic to improve student's understanding of CS2040/C/S material, short break, then for the second half, students will practice solve a "simple" problem (guided by TA) during the next 1-hour/week (effective 45 minutes) lab session of past week X-1 topic to improve student's coding skills. This semester, we only have 8 available options (all on Monday), starting from Wk03,
There are two lecture sessions weekly starting from Wk01:
1. 2-hour/week (effective 95m) in-class lecture 1 on Wed, 10am-12nn @ LT19 (start on time at 10.00am and end by around 11.35am), we will roughly do: 5m (buffer) + 5m (admins) + 35m (fast in class review of the more difficult parts of the designated VisuAlgo e-Lecture topics) + 7m (break) + 30m (application 1 - solving at least 1 Online Judge problem live) + 13m (buffer),
2. 1-hour/week (effective 45m) in-class lecture 2 on Thu, 9-10am @ LT19 too, we will roughly do: 5m (buffer) + 5m (admins) + 30m (application 2 - solving at least another 1 Online Judge problem live) + 5m (buffer) — this additional 35-40m lecture per week is the one that is different from IT5003 version,
Attempt a ~two-weeks Problem Set (PS) @ home, approximately 3 hours of work per week on average or (~6++ hours/set), starting from Wk01. The problems will be discussed in algorithmic (high-level) during each Tut+Lab session. You can use ChatGPT (or alternative) tool if you have spent more than 2 hours any PS task without external help (other human or AI, which means in the 2 hours final assessment, you cannot solve this yet), and as long as you eventually (re-)code the solution yourself (this part is for your own good), Plagiarism checker is built-in inside Kattis and extremely similar code can be easily identified,
TOTALLY OPTIONAL: (Re-)solve some Kattis demo problems (or more) that are related to CS2040/C/S using Prof Halim's Methods to Solve page. WARNING: Doing this will significantly increases your study time per week for this course.

Then, repeat this throughout the semester :).

The S1 AY 2024/25 timetable below is still tentative, especially those that are highlighted with pink color. The Wed morning of CS2040S will be as close as possible with Wed evening of IT5003.

Week	Tutorial+Lab Combo	Lecture	Interesting Problem Set
Cells with course material that have not been updated are highlighted with pink color, past classes more than one week ago are hidden so that we can focus on the current and future classes, but you can restore them by clicking 'Show Past' button above, future classes are not highlighted
-01, 29 Jul-02 Aug	Has Not Started	Has Not Started, but please revise your CS1101S/IT5001/equivalent Prof Halim assumes that all of you have taken or exempted from this course/its variants Register at Kattis (use full name as in Matric card), read Java specific instructions @ Kattis, pick up basic Java by yourself, and solve the selected Online Judge (OJ) Problem Set 0 (PS0) by yourself (CS1101S/IT5001/equivalent level) (solving many 'trivial problems' from this set ---trackable by Prof Halim, indirectly tells him about your CS1101S/IT5001/equivalent rough grade) Dr Chong Ket Fah will run CS2040 placement test for AY24/25 incoming IOI medallists on Fri, 02 August 2024, 9-11am	PS0: Easy Coding Challenges (01-14 Aug) Already graded to speed up registration admins Solve any 3 out of 10 trivial tasks for 1%
00, 05-09 Aug	Has Not Started	Has Not Started Continue attempting PS0 (hints in class Discord) Singapore National Day on Fri, 09 August 2024	PS0, continued Remember, solve any 3 for 1%
01, 12-16 Aug	Has Not Started	01a. Course Admin, (Re-)Introduction to Java Setting the tone for a flipped classroom course VisuAlgo + this Private Canvas + Kattis (NUS) + Kattis (open) Basic Java review/new feature introduction Kattis problem(s) discussed today: A few PS0 tasks (just for warm-up) In the middle of 01a: VisuAlgo Online Quiz 0 (1%) There will be 1 trivial question during the first lecture Bring your own laptop This one is put here to speed-up admins (don't skip the first lecture) Reminder: Read simple algorithms on unsorted array (Slide 1 to 6-1) before the next lecture 01b. Algorithms on Unsorted Array Kattis problem(s) discussed today: rankproblem (a List ADT task; Java ArrayList operations: add (2 versions), indexOf, remove; and using Java class) Reminder: Read sorting intro, algorithm analysis, and O(N^2) sorting algorithms (Slide 1 to 9-3) before the next lecture	PS0 (1%) Due: Wed, 14 Aug 24, 11.29am PS1: Basic Programming Out: Wed, 14 Aug 24, 11.30am Mentioned at the end of the first lecture CS2040S students do problem B+C
02, 19-23 Aug	Has Not Started But (e-)Consultation starts from Fri, 23 Aug Review demo code so far, focusing on Java API (ArrayList, String, Collections)	02a. Analysis of Algorithms (Slide 1 to 9-3) Live SpeedTest.cpp \| py \| java demo (measure runtime, count # of operations, vs asymptotic analysis) Fast review of O(N^2) sorting algorithms Kattis problem(s) discussed today: thanos (analysis: exponential growth, logarithmic steps) mjehuric (bubble sort simulation) height (insertion sort simulation) nothanks (sorting library and linear pass) 02b. Algorithms on Sorted Array Kattis problem(s) discussed today: classfieldtrip (merge of mergesort; or any other solution that works) Last flipped classroom reminder: Read all sorting e-Lecture slides before next lecture	PS1 (2%) Due: Sat, 24 Aug 24, 07.59am PS2: Sorting-related Problems Out: Sat, 24 Aug 24, 08.00am
03, 26-30 Aug	T01+L01: tut01.pdf Introduction, OOP review (List ADT, ListArrayTest.py \| java) Algorithm Analysis, Hands-on, a basic List ADT task, PS1 Debrief (short), PS2 Discussion (algorithmic)	03a. Sorting (Slide 10 to 13-2) O(N log N) Merge Sort algorithm (Java Collections.sort; Python list.sort) Expected O(N log N) (Rand) Quick Sort algorithm (C++ sort; Java Arrays.sort (primitives)) See the details at SortingDemo.cpp \| py \| java Java Collections.sort, Arrays.sort (object), Arrays.sort (primitives) Sorting Online Quiz (medium) Kattis problem(s) discussed today: sortofsorting (custom comparator, stable sorting library) 03b. Sorting Extras (until end) A preview of Ω(N log N) lower-bound of comparison-based sorting algorithms Special-purpose O(N) sorting algorithm: Counting Sort (Only) Other topics of sorting, e.g., counting inversions, counting minimum swaps Prof Halim will depart to Alexandria, Egypt	PS2, continued
04, 02-06 Sep	T02+L02: tut02.pdf Sorting Application(s), Sorting, mini experiment, QuickSelect, ADT/List ADT, VA OQ demo (sorting), Hands-on, sorting applications, PS2 Discussion (algorithmic)	Prof Halim will be in Alexandria, Egypt, for IOI 2024 (01-08 Sep 2024) 04a lecture will be covered by [someone, TBC]. 04b lecture will be covered by [someone, TBC]. 04a. List ADT: SLL/Stack/Queue/DLL/Deque (all slides) Introducing List ADT, (resizeable) array versus SLLDemo.cpp \| py \| java implementation Introducing Stack ADT and MyStack implementation (extension of SLLDemo) Stack, but using Java ArrayList implementation versus Java LinkedList and Stack classes Introducing Queue ADT and MyQueue implementation (another extension of SLLDemo) DLL and Deque ADT Fixed-size array, circular array version, versus Java Queue and Deque interfaces Linked List Online Quiz (medium) A few other LL technicalities 04b. List Review [Live] Review of the recording Kattis problem(s) discussed today: circuitmath (classic postfix evalution; use a stack/LIFO) delimitersoup (classic bracket matching variant; use a stack/LIFO)	PS2 (2%) Due: Sat, 07 Sep 24, 07.59am PS3: List+PQ Problems Out: Sat, 07 Sep 24, 08.00am
05, 09-13 Sep	T03+L03: tut03.pdf Linked List, mini experiment, Applications: Reversing/Sorting a List, Application: Stack-related, PS2 Debrief (short), Java LinkedList/Stack/Queue/Deque, VA OQ demo (list), Hands-on, a list application, PS3 Discussion (algorithmic)	05a. Priority Queue (PQ) ADT: Binary Heap (Slide 1 to 8-2) Introducing PQ ADT Introducing basic Binary Heap structure and its Insert+ExtractMax operations Discussing CreateHeap (two versions) and HeapSort operations BinaryHeapDemo.cpp \| py \| java Java PriorityQueue class; see priority_queue.cpp \| py \| java at GitHub repo of CPbook website Last 15m of 05a: VisuAlgo Online Quiz 1 (7%) Bring your own laptop that can run at least 15 minutes on battery power. (we do not provide any spare laptop). Material: /array (3 Qs), /sorting (3 Qs), /list (3 Qs), and 3 'new' questions. 05b. PQ Extras (until end) Clearing a few more details about Binary Heap O(N) CreateHeap analysis and O(N+K log N) PartialSort Max-to-Min heap conversions (numbers only) Discussing UpdateKey(i, newv) and Delete(i) operations Binary Heap Online Quiz (medium) Prof Halim will depart to Astana, Kazakhstan	PS3, continued
06, 16-20 Sep	T04+L04: tut04.pdf Binary Heap, Max-Min conversion, Additional ADT PQ Operations, Java PriorityQueue, VA OQ demo (heap), Hands-on, a simple problem involving PQ, PS3 last Discussion (algorithmic)	Prof Halim will be in Astana, Kazakhstan, for ICPC World Finals 2024 (15-20 Sep 2024) 06a+06b lectures will be covered by [someone, TBC]. 06a. Table ADT part 1: Hash Table (slide 1 to 10-5) Table ADT and DAT Basic Hashing Concepts Easiest Collision Resolution Technique: CA (SC) Another Collision Resolution Technique: OA (LP) More Collision Resolution Techniques: OA (QP and DH) Comparing CA: SC with OA: DH Other technicalities of Hash Table Hash Table Online Quiz (easy; a bit too tedious on medium/hard settings) 06b. Hash Table Extras (until end) HashTableDemo.cpp \| py \| java (all use SC) Java HashSet/HashMap/Hashtable classes See unordered_map_unordered_set.cpp \| py \| java at GitHub repo of CPbook website Kattis problem(s) discussed today: proofs (a simple table ADT task)	PS3 (2%) Due: Sat, 21 Sep 24, 07.59am PS4: Hash Table Problems Out: Sat, 21 Sep 24, 08.00am
Recess Week, 21-29 Sep 2024 You can take a break this week :)
07, 30 Sep-04 Oct	T05+L05: tut05.pdf [Special] Past midterm paper(s) discussions	First 18m of 07a: Hash Table recording review Then 7m break Next 70m of 07a: Midterm Quiz (11%) Time window: [10.25am-11.35am] (70 minutes). Open book A few short questions (close-ended) and one (hard) essay question No more giveaway questions (the questions are either tricky or hard) There will be a few blank boxes, which will be given 1 mark if left blank, but 0 if answered (even a single character) and declared (very) wrong Material: Up to PQ (L05ab on Week 05 + T04+L04 on Week 06), NO Hash Table yet Midterm Test Past Papers (recent 3 AYs only): AY 2022/23: S1-midterm.pdf, [I didn't teach CS2040C in S2], AY 2023/24: S1-midterm.pdf, [I don't teach CS2040S in S2], AY 2024/25: S1-midterm.pdf (will be our paper), [I don't teach CS2040S in S2]. 07b. Union-Find Disjoint Sets (all slides) Quick Recap with VisuAlgo See unionfind_ds.cpp \| py \| java at GitHub repo of CPbook website Kattis problem(s) discussed today: tildes (basic UFDS task) PS: UFDS will be reused in Connected Component (CC) and MST topics	PS4, continued
08, 07-11 Oct	T06+L06: tut06.pdf Table ADT 1 - unordered, Basic hashing concepts, Hash Table issues, Java HashSet/HashMap, PS3 Debrief (short), Only for CS2040S: UFDS review, VA OQ demo (hashtable,ufds), Skipped for CS2040S: ~~Hands-on, a hash table application,~~ PS4 Discussion (algorithmic)	08a. Table ADT part 2: BST (Slide 1 to 12-1) BST concepts and the various BST operations The multiset idea BST (only) Online Quiz (medium) BSTDemo.cpp \| py \| java Randomly built BST and a preview of balanced BST, e.g., AVL Tree Last 15m of 08a: VisuAlgo Online Quiz 2 (7%) Material: /heap (3 Qs), /ufds (3 Qs), /hashtable (3 Qs), and 3 'new' questions. 08b. Balanced BST and Applications (until end) QnA about AVL Tree concepts BST+AVL Online Quiz (hard; need to clear pre-req) AVLDemo.cpp \| (no py yet) \| java Java TreeSet/TreeMap classes See map_set.cpp \| (no built-in py) \| java at GitHub repo of CPbook website Kattis problem(s) discussed today: kattissquest (combo DS, e.g., TreeMap int to PQ of ints, etc) Prof Halim will depart to Shenzhen, China	PS4 (2%) Due: Sat, 12 Oct 24, 07.59am PS5: Combo DS Problems Out: Sat, 12 Oct 24, 08.00am
09, 14-18 Oct	T07+L07: tut07.pdf Table ADT 2 - ordered, (balanced) BST advanced stuffs: Select and Rank, PQ ADT alternative implementation, Comparison with Table ADT 1: unordered vs ordered, Java TreeSet/TreeMap, PS4 Debrief (short), VA OQ demo (bst or avl (need to clear pre-req)) Hands-on, a combo DS task, PS5 Discussion (algorithmic)	Prof Halim will be in Shenzhen, China, for ICPC Challenge Championship powered by Huawei 09a+b lectures will be covered by [someone, TBC]. 09a. Graph DS (all slides) + DFS Traversal (Slide 1 to 5-8) Implementations of graph DS and its applications Graph DS Online Quiz (medium), No built-in C++ STL container \| Python standard library \| Java API, See graph_ds.cpp \| py \| java at GitHub repo of CPbook website, Early discussion of the basic forms of Graph Traversal algorithms: DFS first + one application (count #CC) See dfs_cc.cpp \| py \| java Kattis problem(s) discussed today: reachableroads (AL; count #CC; DFS introduction) 09b. Graph Traversal Applications (Slide 7-3 to 7-8) Finding Connected Components on Grid Graph Detecting cycle in a Directed Graph Kattis problem(s) discussed today: amoebas (finding CCs on implicit (grid) graph) runningmom (AL of strings; DFS; back edge detection)	PS5, continued
10, 21-25 Oct	T08+L08: tut08.pdf Graph DS Review, Some Graph Properties Discussion, Graph DS Conversion Exercise, DFS Review, Only for CS2040S: UFDS revisited, Custom graph DS implementation review, VA OQ demo (graphds,dfsbfs), Hands-on, a simple Graph DS task, PS5 Discussion (algorithmic)	10a. Graph Traversal Applications (Slide 6 to 7-11) Review DFS and introducing BFS Focus on a few more basic DFS/BFS applications (we skip slide 8-12, out of CS2040/C/S and IT5003 scope) DFS/BFS Online Quiz (medium) No built-in C++ STL algorithm \| Python standard library \| Java API, See UVa00469.cpp \| py \| java, and bfs.cpp \| bfs.py \| java at GitHub repo of CPbook website, Kattis problem(s) discussed today: builddeps (AL of Strings + postorder DFS toposort demo) 10b. Practical Exam (11%) Thu, 24 Oct 2024, 8.55-9.55am (60m) (LT19 is empty before 9am and between 10-11am) Just one task with a bit more of subtasks (instead of two tasks in two hours) All other details TBA. NUS Online Teaching Feedback opens this Fri But this timing is too early for our course... You can wait until you have done VA OQ 3	PS5 (2%) Due: Sat, 26 Oct 24, 07.59am PS6: Graph Problems Out: Sat, 26 Oct 24, 08.00am
Make-up time window Those who miss VisuAlgo Online Quiz 1 on Week 05, Midterm Quiz on Week 07 or VisuAlgo Online Quiz 2 on Week 08 due to VALID reasons (valid Medical Certificate; representing NUS for an official event; bereavement of immediate family member) will do make up on Week 10 (details only for those eligible). Note that there is no more make up of make up :O...
11, 28 Oct-01 Nov	T09+L09: tut09.pdf BFS Review DFS/BFS advanced stuffs: Cycle Detection, Toposort++, Floodfill/CC, Modeling exercise, PS5 Debrief (short), VA OQ demo (dfsbfs), CS2040S Only: short PE debrief by TA, Hands-on, a Graph Traversal task, PS6 Discussion (algorithmic)	11a. SSSP Problem (Slide 1 to 7-5) Review of basic SSSP problem Preview of O(VE) / O(kE) Bellman-Ford algorithm QnA on BFS algorithm for unweighted SSSP SSSP Online Quiz (medium) QnA on Dijkstra's algorithm (modified Dijkstra's first) See dijkstra.cpp \| py \| java at GitHub repo of CPbook website Kattis problem(s) discussed today: modulosolitaire (SSSP; unweighted graph; BFS; implicit graph) shortestpath1 (basic Dijkstra's) Thu, 31 Oct 2024 is Deepavali PH CS2040S 11b lecture is cancelled Additionally, Fri, 01 Nov 2024 is chosen as NUS well-being day S1 AY 2024/25 Enjoy our short break here	PS6, continued
12, 04-08 Nov	T10+L10: tut10.pdf BFS/Dijkstra's review Modeling exercises (continued), VA OQ demo (sssp), Hands-on, an SSSP task, PS6 Discussion (algorithmic)	12a. MST Problem (Slide 1 to end) Review of basic MST problem QnA on Kruskal's and Prim's algorithms Mix and Match of various data structures/algorithms covered so far Kattis problem(s) discussed today: cats (MST application) Onsite class photo as momento Last 15m: VisuAlgo Online Quiz 3 (7%) Material: /bst (3 Qs), /graphds (3 Qs), /dfsbfs (3 Qs), /sssp (3 Qs). 12b. SSSP+MST Wrap-Up QnA on Bellman-Ford algorithm (the general algorithm) QnA on other special cases of SSSP problem Other MST Variants	PS6 (2%) Due: Sat, 09 Nov 24, 07.59am
13, 11-15 Nov	T11+L11: tut11.pdf VA OQ demo (mst), Class Photo (for momento) Tut+Lab participation marks given (3%)	13a. Make-up (or Remedial) Practical Exam slot Wed, 13 Nov 2024 (09.35-11.35am, 120m) Venue: LT15 (TBC) --- need to ensure there is no class at 9-10am Details only given to those who are invited. Make-up VisuAlgo Online Quiz 3 Venue and Timing TBC 13b. The Last Lecture Course wrap-up et al: Undoing all the illegal Java coding techniques, Semester summary, Review of what can be done better for future iterations, Advertisement of future (algorithm) courses: CS3233 (S2) or CS3230 (S1) Advertisement for part-time TA jobs (A-/A/A+ only), Ending: a few Final Assessment Tips.	No more :) Or attempt the optional Final Preparation Tracker
Study Week, 16-22 Nov 2024 Final Assessment Consultations (per request) Final Assessment Past Papers (recent 3 AYs only, note the transition from CS2040C/C++ to CS2040S/Java): AY 2022/23: S1-final.pdf, [Prof Halim didn't teach CS2040C in S2], AY 2023/24: S1-final.pdf, [Prof Halim didn't teach CS2040S in S2], Final Preparation Tracker AY 2024/25: S1-final.pdf (will be our paper; maybe also try IT5003 S1-final, link TBA), [Prof Halim didn't teach CS2040S in S2]. NUS Online Teaching Feedback System closes on Friday of Study Week
Final Assessment (40%) Date and Time: Wed, 27 Nov 2024, 5.00-7.00pm Venue: TBA Open book 40% MCQs (extremely tricky) (the MCQs are there to speed up grading as Prof Halim has two other final assessments on 13 Nov (14 pax) and 29 Nov (392 pax)) 2 questions with shorter answers, the easier ones (20%) 3 application questions, the harder ones (40%)

CS2040S - Data Structures and Algorithms (Java)