Com ompSci ci 201, 201, First D Day Susan Rodger January 10, - - PowerPoint PPT Presentation

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Com ompSci ci 201, 201, First D Day Susan Rodger January 10, - - PowerPoint PPT Presentation

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Com ompSci ci 201, 201, First D Day Susan Rodger January 10, 2019 Website: http://bit.ly/201spring2020 1/10/2020 CompSci 201, Spring 2020 1 Course Information Online Compsc sci/I /Int nter erne net: : http:/ ://bit it.ly/201s

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SLIDE 1

Com

  • mpSci

ci 201, 201, First D Day

Susan Rodger January 10, 2019

1/10/2020 CompSci 201, Spring 2020 1

Website: http://bit.ly/201spring2020

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SLIDE 2

Course Information Online

  • Compsc

sci/I /Int nter erne net: : http:/ ://bit it.ly/201s /201spring ing2020 2020 ak aka

https://w ://www2.cs cs.duke.edu .edu/co /courses es/s /spr pring20/co /comps psci201/

  • Sakai

1/10/2020 CompSci 201, Spring 2020 3

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SLIDE 3

A is for …

  • Algorithm
  • This course is: Data Structures + Algorithms
  • API
  • Using Libraries is the future

1/10/2020 CompSci 201, Spring 2020 5

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SLIDE 4

PFTD: Plan For the Day

  • Be able to articulate why 201 is the right course

for you, in terms of being able to complete it with understanding

  • What are pre-requisites?
  • Be able to explain what work is expected,

collaboration policies, exams, discussions, assignments, APTs

  • Why are you taking Compsci 201?

1/10/2020 CompSci 201, Spring 2020 6

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SLIDE 5

PFTD: Part II

  • Be able to read some Java programs and to

analyze them by applying your knowledge of programming to Java programs

  • Analyze for understanding and prediction
  • Know what work you should complete before

January 13, 15, and 16

  • What is due, when is it due

1/10/2020 CompSci 201, Spring 2020 7

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SLIDE 6

What is Computer Science?

1/10/2020 CompSci 201, Spring 2020 8

“Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works.”

  • Carl Sagan
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SLIDE 7

Algorithms and Data Structures

1/10/2020 CompSci 201, Spring 2020 9

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SLIDE 8

Course Staff

  • Teachi

aching ng A Associa ciate:

  • Kate O'Hanlon
  • Teachi

aching ng A Assis istant nts: :

  • Yongxin Tan, Carol Yang
  • Head U

d UTAs As:

  • Belanie Nagiel, Megan Phibbons, Charles Lyu,

Daniel Hwang

  • 26

26 UTAs: s see ee co cour urse w web ebsite

1/10/2020 CompSci 201, Spring 2020 10

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SLIDE 9

What is Computer Science?

  • Grou
  • ups of
  • f 2-4, Do NOT use a search engine
  • http://bit.ly/201spring20-0110-1
  • How is this relevant to Compsci 201?
  • Tradeoffs in scaling Data Structures/Algorithms
  • WOTO

1/10/2020 CompSci 201, Spring 2020 12

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SLIDE 10

What is Computer Science?

1/10/2020 CompSci 201, Spring 2020 13

3.5 billion snaps/day or 40,000 second 350 million photos to FB/day 100 million Instagram updates/day 5.6 billion Google searches/day

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What is Computer Science?

What is it that distinguishes it from the separate subjects with which it is related? What is the linking thread which gathers these disparate branches into a single discipline? My answer to these questions is simple --- it is the art of programming a computer. It is the art of designing efficient and elegant methods of getting a computer to solve problems, theoretical or practical, small or large, simple or complex.

C.A.R. (Tony)Hoare

1/10/2020 CompSci 201, Spring 2020 14

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What is Computer Science?

  • It is t

the s study of auto tomati ting a algorith thmic p processe sses s that s scale ale

  • Long Division?
  • Updating Search Engine information?
  • Adding up a column of numbers?
  • Sending $$ via Venmo?
  • Updating your LinkedIn page?

1/10/2020 CompSci 201, Spring 2020 16

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SLIDE 13

Some Goals for 201

  • Given a problem statement & a real data

source, design, develop, debug, and test a Java program that uses appropriate standard libraries to efficiently solve the problem.

  • Write programs that effectively implement and

use data structures such as: arrays, maps, linked lists, stacks, queues, trees, and graphs.

1/10/2020 CompSci 201, Spring 2020 17

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SLIDE 14

More Goals for 201

  • Evaluate the time and space complexity of

algorithms, especially algorithms that scale, using empirical and mathematical analysis.

  • Apply basic object-oriented design and

programming principles in developing software

1/10/2020 CompSci 201, Spring 2020 18

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Who are you?

1/10/2020 CompSci 201, Spring 2020 19

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Latanya Sweeney

I am a computer scientist with a long history of weaving technology and policy together to remove stakeholder barriers to technology adoption. My focus is on "computational policy" and I term myself a "computer (cross) policy" scientist. I have enjoyed success at creating technology that weaves with policy to resolve real-world technology-privacy clashes. http://latanyasweeney.org/ Identify 87% of US population using (dob,zip,gender). Prof. Government and Technology @ Harvard, instrumental in HIPAA because if de-identification work. Former CTO of the FTC

1/10/2020 CompSci 201, Spring 2020 28

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Code Interlude

  • First 2

201 J Java p a pro rogra gram m – maybe f first e t ever!

  • Use what you know
  • Make informed assumptions
  • When more time? Book, Internet, Friends, Brain
  • All

ll code o

  • nlin

nline: w web ebsite and and G Git itLab

  • Browse, fork, clone, critique, …

1/10/2020 CompSci 201, Spring 2020 29

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SLIDE 18

What does Code do? WDCD

1/10/2020 CompSci 201, Spring 2020 32

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SLIDE 19

Understanding Repetition

  • When

hen d does es lo loop ter erminate?

  • What takes

es t time w e when t n this is c code execut ecutes es?

1/10/2020 CompSci 201, Spring 2020 33

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Java Variables and Types

  • Variab

iables les: n name, t , type, va value ue

  • Primitives: int, double
  • wcount, start, end
  • Object: String, Scanner, HashSet
  • s, set, word
  • For r

reach v ach variab iable/ le/objec ect: n name, t , type, , va value ue

  • What are the operations on these?

1/10/2020 CompSci 201, Spring 2020 34

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Understand and Explain

  • "kjv10.

10.txt" w " with 8 h 823,135 ,135 words, 3 , 34,027 u 027 unique ue

  • About one second to run on rodger laptop
  • Double

le, T Triple le, Q , Quadrup uple le o

  • riginal f

inal file

  • Total # words different, # unique same
  • N words in "kjv10", 2N, 3N, 4N respectively
  • Run

untim imes: 1, 1, 1.5 1.5, 2.0, 2.0, 2.5 2.5 --

  • - pat

attern s n simila ilar

  • How to justify empirical with analytical analysis?

1/10/2020 CompSci 201, Spring 2020 35

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SLIDE 22

From Analysis to Code

  • How to und

understand ( (rea ead) and and c create ( (writ ite)

  • Read book, use Google? read book, ask
  • What book? See syllabus
  • Practice, practice, practice
  • We

e will lo ill look a at a a hig high-le level t el today, m , more d det etails ails i in Dis iscussion M Mond nday and and L Lec ecture Wed edne nesday

  • Pre-discussion work

1/10/2020 CompSci 201, Spring 2020 36

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SLIDE 23

Java Types and Operations

  • Wha

hat can an we e do wit ith int int and and d doub uble?

  • +,-,/ seen in code, many more
  • Initialize and update
  • Wha

hat c can w an we e do wit ith HashSet?

  • .add(..), .contains(..), .size()
  • What c

can w we do with h Scanner anner?

  • .hasNext(), .next(), .close()

1/10/2020 CompSci 201, Spring 2020 37

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Java Concepts and Conventions

  • Class

sses a s and Objects

  • You invoke methods on … call functions on ..
  • Object dot method: set.add(..) or

s.hasNext() or set.size() or …

  • Variab

iable i le ident ntif ifier iers b begin w in with l lowercase l e let etter er

  • Class i

ident ntif ifie iers b begin w in with u h uppercase l let etter

  • Statements end

end in s in sem emi-colo lon, n, s statem ement ent b blocks crea eated ed b by brace ces: { {..}

1/10/2020 CompSci 201, Spring 2020 38

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WOTO

http:// //bi bit.ly/2 /201spr pring20-01 0110 10-2

1/10/2020 CompSci 201, Spring 2020 39

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Understanding Java and Scale

  • Java is

is an o an object-orient iented ed l lang ngua uage

  • More on classes and objects later
  • Primit

itiv ive t e types: int int, d , double, c char ar, , boolean an, , …

  • Fast, small, values stored in memory
  • Arrays a

are h homogene eneous us collectio ions ns

  • Like Python lists, Matlab array/vector
  • Once created, don’t grow, can hold primitives
  • Arra

rrayList<>, S , Set<>, M Map<> a are c collec lectio ions ns

  • Dynamic, powerful, scale, no primitives

1/10/2020 CompSci 201, Spring 2020 40

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SLIDE 27

Analyzing Code, Algorithm

  • Wha

hat file o ile of 1,00 1,000,000 00 s strings w will r ill res esult in in this his code e e execut ecuting ing m most q quick ckly ly?

  • Characteristics of file? Bottleneck of method?
  • Wha

hat file o ile of 1,00 1,000,000 00 s strings w will r ill res esult in in this his code e e execut ecuting ing m most s slowly?

1/10/2020 CompSci 201, Spring 2020 41

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Tradeoffs

  • What l

line e is “bottlenec leneck” in this c code/alg lgorit ithm hm?

  • How can we make this faster?
  • Why is Google so fast when searching?
  • Replace

lace HashSet<..> wit ith h ArrayList<..>

  • Why does code still run?
  • Common API, valuable for programmer!!

1/10/2020 CompSci 201, Spring 2020 42

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Course Logistics

  • Please s

e see c e course w websit ite f e for m most m mat ater eria ial/d l/dates es

  • Web:
  • http://bit.ly/201spring2020
  • For gra

r grades

  • Sakai:
  • Exa

Exams:

  • February 14, April 3, April 30 (final)

1/10/2020 CompSci 201, Spring 2020 43

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Course Logistics

  • Please s

e see c e course w websit ite f e for d due d dates es/g /grad ading ing

  • APT Quizzes, Midterm and Final Exams are

assessments

  • Assignments and APTs are where you will

practice and learn the material on your own

  • Discussion – practice and think together
  • Please n

e note collab aboratio ion p n policie cies, A , APT quiz izzes, la late p polic licies, w why hy you u sho houl uld c come t to cla lass

1/10/2020 CompSci 201, Spring 2020 44

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SLIDE 31

Succeeding in 201

  • Come to

to class ss and parti ticipate: WOTO

  • Only one in the group fills out the WOTO
  • Put in all netids from the group
  • Start w

work ear early, g get help help w when hen need needed

  • Initia

ial l l lat ate p e penalt alties ies a aren' n't h harsh, h, o

  • n-ti

time d doesn't 't matter, b but ut no not d doing ing a assignments is is a a bad ad id idea ea

  • Ask if you have any reason to ask, any reason

1/10/2020 CompSci 201, Spring 2020 45

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Success in 201 is …

1/10/2020 CompSci 201, Spring 2020 46