1. Welcome to COMP 250 Introduction to Computer Science! Mathieu Blanchette

2. COMP250 Home Page - Winter 2012 Key course info: Instructor: Mathieu Blanchette Schedule: MWF 9h35-10h25 in MAASS 112 Web page: http://www.cs.mcgill.ca/~blanchem/250 Prerequisites: –Familiarity with a high level programming language and CEGEP level mathematics. –NOTE: COMP 203 and COMP 250 are considered to be equivalent from a prerequisite point of view, and may not both be taken for credit. Computer Science Major and Honours students are strongly advised to take COMP 250 instead of COMP 203. Office hours: Tuesday 11:00-12:30, Friday 10:30-12:30 in Trottier 3107. Teaching assistants: TBD

3. Schedule of topics covered + All lecture notes: http://www.cs.mcgill.ca/~blanchem/250/schedule.html Bulletin board, announcements, discussions: WebCT CE. You can log in at http://www.mcgill.ca/webct Required text: Allen B. Downey How to think like a computer scientist - Java version. http://www.greenteapress.com/thinkapjava/thinkapjava.pdf Suggested textbook: Michael T. Goodrich, Roberto Tamassia Data Structures and Algorithms in Java (Fourth Edition), John Wiley and Sons; NOTES: - Many students found the lecture notes sufficient. - The 2 nd /3 rd editions of the same book is equally good

4. 6 assignments, worth 5% each, for a total of 30% In-class midterm exam #1, on Feb. 8th, worth 10% In-class midterm exam #2, on March 12th, worth 10% 3-hour final exam, on December ??th, worth 50% Policy on late homework Unless a medical justification is given, late assignments will be penalized by 20% per day: 0-24h late: 20%, 24h-48h late: 40%... For some assignments, no late turn in will be accepted. Policy on homework collaboration It is OK to discuss homework questions with others students BUT Everything you take out of a discussion must IN YOUR HEAD (nothing written)! You have to write your solutions by yourself. Anything else is cheating! Course evaluation

5. Integrity and French McGill University values academic integrity. Therefore all students must understand the meaning and consequences of cheating, plagiarism and other academic offences under the Code of Student Conduct and Disciplinary Procedures (see www.mcgill.ca/integrity for more information). In accord with McGill University’s Charter of Students’ Rights, students in this course have the right to submit in English or in French any written work that is to be graded.

6. My work as a researcher

7. Algorithms A systematic and unambiguous procedure that produces - in a finite number of steps - the answer to a question or the solution of a problem. Algorithms can be run on a computer, but they don’t have to: –Mayas had algorithms to predict solar eclipses centuries in advance –Egyptians had algorithms to build pyramids –Indians had algorithms for factorizing polynomials –Greeks had algorithms to build all kinds of geometric construction using only a compass and straight lines.

8. Compass and straight-line construction Problem: Angle bisection INPUT: An angle defined by three points AOB OUTPUT: A point C such that AOC = BOC Algorithm: – Draw circle centered at O to find A’ and B’ – Draw circles centered at A’ and B’ of the same radius to find C – Then AOC and BOC bisect AOB A O B A’A’ B’B’ C

9. Problem: Butterfly Origami INPUT: 2:1 rectangle OUTPUT: A butterfly

10. Problem: Chickpea cooking INPUT: Ingredients (left) OUTPUT: Yummy (but spicy!)

11. To think about… Think of three different ways to solve the following problem: PROBLEM: LIST INTERSECTION Input: –A long list of students taking COMP250 –An long list of students taking MATH240 Output: –How many students are taking both classes? Assume that you only have names, no ID number, and that comparing one name to another takes time because they are written in really small font