COS 126 Exam 2 Information, Spring 2013

Q+A.

There will be a Q+A session Sunday night, April 28, 7:30 pm, Friend 101.

Written exam rules.

50 minutes, during lecture on Tuesday, April 30 at 10am or 11am.
Closed book, closed note.
You may bring one 8.5-by-11 sheet (two sides) with notes in your own handwriting to the exam.
No calculators, computers, or communication devices.
No makeup exams will be considered without the recommendation of a Dean.

Written exam rooms.

You MUST take the exam in your assigned room at the assigned time. We reserve the right to disqualify or penalize those who do not comply in either regard.
Students in precepts P01, P01A, P01B, P02, P02A, P02B, P02C, P02D, P03, P03A will take the written exam in Friend 101.
Students in precepts P04, P04B, P05, P06, P07, P07A, P07B, P08, P08A, P09 will take the written exam in McCosh 10.
You must take the exam at the same time as the lecture for which you are officially enrolled.
(L01 is the 10am lecture. L02 is the 11am lecture.)

Programming exam rules.

90 minutes, on Monday, April 29, 7:30-9:00pm.
Open book, open note, open computer, open browser— but only our course website! Of course, no internal or external communication is permitted (e.g., talking, email, IM, texting, cell phones) during the exam.
Bring your laptop and make sure the battery is fully charged (There are not accessible power outlets in the room.)
Students who have a non-COS class on Monday nights should attend their regularly scheduled class. Contact David Pritchard (dp6@cs.princeton.edu) to schedule a Tuesday makeup exam.
Students who have an Organic Chemistry exam on Monday night, April 29 should take their chemistry exam on Monday night. Contact David Pritchard (dp6@cs.princeton.edu) to schedule a Tuesday makeup exam.
Set up an empty directory on your laptop that allows use of: StdIn.java, StdOut.java, StdDraw.java, ST.java, Stack.java and Queue.java.
With the exception of students who have a verified class conflict or the Organic Chemistry exam listed above, NO makeup exams will be considered without the recommendation of a Dean.

Programming exam rooms.

You MUST take the exam in your assigned room at the assigned time or you will receive no credit.
If you do not have a working laptop (e.g., Java programming environment installed, wireless connectivity in your exam location, battery lasts for a full hour and a half), you MUST contact David Pritchard (dp6@cs.princeton.edu) by April 24 to make alternate arrangements. Please specify whether you need to use a cluster machine or if you simply need access to a power outlet.
Students in P01, P01A, P01B, P05 who have a working laptop will take the programming exam in COMPU 104 on Monday, April 29 at 7:30pm.
Students in P03, P03A who have a working laptop will take the programming exam in COMPU 105 on Monday, April 29 at 7:30pm.
Students in P02, P02A, P02B, P02C, P02D, P06, P07, P07A, P07B, P09 who have a working laptop will take the programming exam in McDonnell A02 on Monday, April 29 at 7:30pm.
Students in P04, P04B, P08, P08A who have a working laptop will take the programming exam in McDonnell A01 on Monday, April 29 at 7:30pm.
Students without working laptops, who have contacted David Pritchard as described above, will take the exam in Friend 016 at the normal time.
Students who need access to a power outlet, who have contacted David Pritchard as described above, will take the exam in either Friend 004 or Friend 016 (whichever room David emails them about) at the normal time.
If you plan to use a cluster machine in Friend 016 for your exam, make sure you know how to use a cluster machine and set up a directory for the exam on your university H: drive that includes a copy of StdIn.java, StdOut.java, StdDraw.java, ST.java, Stack.java, Queue.java. Here is a link to some helpful instructions.

Material covered.

The exam will cover all material in the course, but with an emphasis on the second half of the course (i.e., the material since the first exam):

Scientific Computing: Introduction to Programming in Java, Booksite 9.1, 9.4, 9.5
OOP and ADT: Introduction to Programming in Java, Sections 3.1-3.3, 3.5(booksite), 4.3, 4.4.
Theory: Introduction to Programming in Java, Booksite 7.2-7.7
RE and DFA: On-line Chapter 7 (link on Lecture page).
On-line Circuits Packet (link on Lecture page).
Lecture notes 12-22.
Programming assignments 5-8.

The written part of the exam (in lecture) covers all of the above. It will be multiple-choice or short answer questions on the important material. The best way to prepare for this part of the exam is to read the book and the on-line packets, study the lecture notes, and practice taking old exams. (See Old Exams section below.)

The Monday evening part of the exam is strictly about programming. You will be asked to write a program from scratch (a mini programming assignment). Given the time limitation, this program will not be conceptually difficult, just a test of your ability to write a program that solves a simple problem. The best way to prepare for this part of the exam is to program: Work a few of the exercises in the book and on the booksite that call for writing small programs.

List of topics.

This list is a summary of the main topics on the exam, for your use as a checklist when studying. Do you understand the basic ideas behind each of these topics? Do you know the names and contributions of the major players? If not, reread the appropriate sections in the book and lecture slides.

Scientific computing
- floating point
- roundoff error and catastrophic cancellation
- stable algorithms and well-conditioned problems
Using data types
- declaring variables
- invoking constructors
- invoking methods
- reference types vs. primitive types
Creating data types
- instance variables
- constructors
- instance methods
Designing data types
- encapsulation (public/private)
- static constants
- modular programming
- immutability
Data structures and algorithms
- linked structures (linked lists and binary trees)
- stacks and queues
- symbol tables and binary search trees
- enhanced for loop to iterate through objects (see p. 588 and p. 629)
- which data structure is appropriate for which application
- analysis of algorithms
Theory of computing
- regular expressions (the 5 basic ops, the + operator)
- DFAs (tracing and understanding, but not designing)
- Turing machines (tracing and understanding, but not designing)
- duality, universality, Church-Turing thesis, computability, halting problem
- Intractability (P, NP, NP-complete, P = NP question, extended Church-Turing thesis, reduction)
Combinational circuits and Architecture
- Boolean logic
- AND, OR, NOT gates
- sum-of-products
- Sequential circuits
- SR flip-flops
- Multiplexer, Decoder
- TOY architecture
- Processor design
APIs.
You should be familiar with the following static methods (the ones we've encountered frequently in the lectures and assignments). If we want you to use some other library function, we'll remind you how it works.
```
Math.sqrt()
Math.max()
Math.min()
Math.abs()
Math.sin()
Math.cos()
Math.exp()
Math.pow()
Math.log()
Math.random()
Math.round()
Math.ceil()
Math.E
Math.PI

Integer.parseInt()
Integer.MAX_VALUE
Integer.MIN_VALUE
Double.parseDouble()
Double.POSITIVE_INFINITY
Double.NEGATIVE_INFINITY

StdOut.println()
StdOut.print()
StdOut.printf()

StdIn.readInt()
StdIn.readDouble()
StdIn.readString()
StdIn.isEmpty()
StdIn.readAll()

StdDraw.line()
StdDraw.point()
StdDraw.circle()
StdDraw.square()
StdDraw.setXscale()
StdDraw.setYscale()
StdDraw.clear()
StdDraw.show()
StdDraw.picture() 
StdDraw.polygon()
StdDraw.filledPolygon()
StdDraw.rectangle()
StdDraw.filledRectangle()
```
You should also be familiar with the following data types and instance methods:
```
String data type:  charAt(), substring(), matches(), indexOf(), length(), equals()

Picture data type: width(), height(), get(), set(), show()

Queue data type: isEmpty(), enqueue(), dequeue(), size(), iteration

Stack data type: isEmpty(), push(), pop(), size(), iteration

ST data type: put(), get(), contains(), size(), iteration
```
Old Exams.

A good way to practice for the EXAM is to solve problems from old exams.
Warning 1: Some old exams include questions on topics that we have not covered this semester, for example percolation and Quicksort.
Warning 2: Studying questions that ask you to write code is worthwhile, but bear in mind that some of the old exams were two hours, closed book, no computers. When looking at an old exam, check the cover sheet to see if it was a 50 minute exam or a 2 hour exam. This term, the written exam will not have questions that ask you to write a significant amount of code. The purpose of the programming exam is to test your ability to write code.

Updated April 25, 2013.