1. Instructor: Xenia Mountrouidou
CS 340 Data Structures
Instructor: Xenia Mountrouidou

2. Who am I? Dr. X – Computer Scientist
CS150
Who am I?
Dr. X – Computer Scientist
PhD at North Carolina State University – Optical networks performance
Worked for IBM – Software Performance Engineer
Post doc at College of William and Mary
Scuba diver, manga comics collector, science fiction reader.

3. CS150
Who am I?

4. Course Objectives At the end of this class you will be able to:
CS 340
Course Objectives
At the end of this class you will be able to:
Make design decisions on which data structure is best to use regarding
performance,
memory, and
implementation efficiency.
Devise or use the most efficient algorithm in your projects.
Understand algorithmic complexity.
Think analytically and identify complexity of a program.

5. Course Objectives (cont.)
CS 340
Course Objectives (cont.)
At the end of this class you will be able to:
Apply object oriented programming principles when you develop software.
Use and understand third party code.
Detect inefficiency of data structures and algorithms of third party code.
Develop projects using agile test driven approach (Junit).
Employ the Java API.
This class uses Java. It is not ABOUT LEARNING JAVA!!

6. Why do you need CS 340? Scenario:
You are a senior developer for Amazon.
You are working on their e-commerce application server!
You are a java guru, OO programming is second nature to you… but you do not understand data structures and algorithms.
BIG DEAL! Everything runs perfectly. Until one day…
You need to use a sorting algorithm to sort all potential sellers of a product based on price or ranking or relevance.

7. Why do you need CS 340? Scenario (cont.): Software is not just coding…
On every click for a product search, your sorting algorithm will be used.
You choose bubble sort. After all, it has a cool name!
Let’s see what happens:
Software is not just coding…
It is design, performance, memory consumption
It is an art, a riddle to be solved with every project
You need to know about data structures not just to write good code, but to analyze, design and develop good software.
Good code follows from good software. Good software comes from good design, and good design relies on a slew of fundamental concepts, data structures and algorithms being one of them.
This applies to Java or C or whatever.

8. More motivation Social networks Do you know how Google search works?
CS 340
More motivation
Social networks
Do you know which data structures FB developers are using?
Which data structure is better to use for a social network?
Do you know how Google search works?
What is the best algorithm and why?
Do they use any data structures?
Have you heard about Big Data?

9. CS 340
Lectures
We meet at 11:00-12:45, every Tues/Thurs, at Merritt Penticoff Science Bld, Room 116A
Check the schedule on the class webpage
Reading and examples will be posted online
Lectures will be interactive. This means:
You will need to study the new material before every lecture (slides and book or online material)
We will have a lab every week, you will need to code
You will have a test every week:
A couple of questions on last week’s topics
A couple of questions about current week’s topics

10. Lectures I will not talk more than half an hour (hopefully!)
CS 340
Lectures
I will not talk more than half an hour (hopefully!)
During lectures I will demonstrate coding
Your questions are important!
However, you should not interrupt the flow of class
I will have specific slides/time during lecture or coding when you can ask questions

11. CS 340
Electronic Devices
You may use your laptop to take notes and complete programming assignments during class
You will use the classroom computers to take tests
Smart phones will be on silent mode during class time
You may record the lectures
Great question from JD!
You will need to setup your laptop to make it usable for class else use the school computer

12. CS 340
Questions?

13. CS 340
How to get help
Join my office hours at MP 203 (2nd floor)
Monday 1:00 - 3:00 pm,
Tuesday 9:00-11:00 am, and
Thursday 1:00-2:00 pm
Use the tutoring sessions at the CS Society meetings (schedule will be announced soon)
Use the tutor’s office hours (schedule will be announced soon)
Set an appointment with me via (xmountr at ju.edu)
Use the textbooks:
Data Structures and Algorithm Analysis in Java, Mark Allen Weiss, 3rd Edition, Pearson
Thinking in Java, Bruce Eckel, 3rd Edition. Free E-Book and textbook website.
Experiment with code. It’s fun…

14. Grading Final exam 25% Homework 20% Programming projects 30% Tests
CS 340
Grading
Final exam
25%
Homework
20%
Programming projects
30%
Tests
Total
100%
Homework and Programming Projects will be posted online on BlackBoard and on the class website
You will upload your completed assignments on BlackBoard

15. Programming Projects They involve These will be done in pairs
CS 340
Programming Projects
They involve
Data Structures & Algorithms
Design
Coding
Testing
Debugging
These will be done in pairs
You need to send me an until the end of the second week of classes with your team members
I will assign teams if you do not find a team
Each team member will evaluate his/her team mate
Each team member will contribute equally to coding, design, and testing

16. Homework It will involve: Homework will be completed individually
CS 340
Homework
It will involve:
Analytical thinking
Computational thinking
A little bit of math
Homework will be completed individually

17. CS 340
Policies
Cheating means “submitting, without proper attribution, any computer code that is directly traceable to the computer code written by another person.”
Or even better:
“Any form of cheating, including concealed notes during exams, copying or allowing others to copy from an exam, students substituting for one another in exams, submission of another person’s work for evaluation, preparing work for another person’s submission, unauthorized collaboration on an assignment, submission of the same or substantially similar work for two courses without the permission of the professors. Plagiarism is a form of Academic Misconduct that involves taking either direct quotes or slightly altered, paraphrased material from a source without proper citations and thereby failing to credit the original author. Cutting and pasting from any source including the Internet, as well as purchasing papers, are forms of plagiarism.”
I give students a failing homework grade for any cheating.
A second cheating attempt will be escalated

18. CS 340
Policies
You may discuss homework problems with classmates, after you have made a serious effort in trying the homework on your own.
You can use ideas from the literature (with proper citation).
You can use anything from the textbooks/notes.
The code you submit must be written completely by you.

19. Policies Read the collaboration policy carefully. Late policy:
CS 340
Policies
Read the collaboration policy carefully.
Late policy:
1% is reduced by every day the homework is late
I will use software to find if there is illegal collaboration

20. Principles of Pair Programming
CS 340
Principles of Pair Programming

21. Principles of Pair Programming
CS 340
Principles of Pair Programming
All I Really Need to Know about pair programming I Learned in Kindergarten
Share everything.
Play fair.
Don’t hit people.
Put things back where you found them.
Clean up your own mess.
Don’t take things that aren’t yours.
Say you’re sorry when you hurt somebody.

22. Principles of Pair Programming
CS 340
Principles of Pair Programming
Wash your hands before you eat.
Flush.
Warm cookies and cold milk are good for you.
Live a balanced life – learn some and think some and draw and paint and sing and
Dance and play and work every day some.
Take a nap every afternoon.
When you go out into the world, watch out for traffic, hold hands and stick together.
Be aware of wonder.

23. Programming languages… a bit of history
CS 340
Programming languages… a bit of history

24. Programming Language Evolution
CS 340
Programming Language Evolution
1st generation: Machine language
2nd generation: Assembler
3rd generation: COBOL, FORTRAN, C, ALGOL, BASIC, C, C++, C#, Pascal, Ada and … Java
4th generation: SQL, spreadsheets, Mathematica, MATLAB, SAS
5th generation: (example, anyone?)

25. Why So Many Languages? Bring the language “closer” to the problem.
CS 340
Why So Many Languages?
Bring the language “closer” to the problem.
But 4GLs are typically focused on specialized domains (e.g., relational databases).
We want a language that is general purpose, yet can easily be “tailored” to any domain.

26. CS 340
Questions?

27. CS 340
Java vs C#

28. Java vs C# Not so different from each other
CS440
Java vs C#
Not so different from each other
C# versus Java : syntactic differences
C# versus Java : a developer's perspective

29. Java vs C#: Program Structure
package hello;
public class HelloWorld {
public static void main(String[] args) {
String name = "Java";
// See if an argument was passed from the command line
if (args.length == 1)
name = args[0];
System.out.println("Hello, " + name + "!"); }
using System;
namespace Hello {
public static void Main(string[] args) {
string name = "C#";
if (args.Length == 1)
Console.WriteLine("Hello, " + name + "!");

30. Java vs C#: Comments Java C# // Single line /* Multiple line */
/** Javadoc documentation comments */
/// XML comments on a single line
/** XML comments on multiple lines */

31. Java vs C#: Data Types Java C# Primitive Types boolean byte char
short, int, long
float, double
Reference Types
Object (superclass of all other classes)
String
arrays, classes, interfaces
Value Types
bool
byte, sbyte
short, ushort, int, uint, long, ulong
float, double, decimal
structures, enumerations
object (superclass of all other classes)
string
arrays, classes, interfaces, delegates

32. Java vs C#: Data Types Java C# Conversions // int to String
int x = 123;
String y = Integer.toString(x); // y is "123"
// String to int
y = "456";
x = Integer.parseInt(y); // x is 456
// double to int
double z = 3.5;
x = (int) z; // x is 3 (truncates decimal)
// int to string
String y = x.ToString(); // y is "123"
// string to int
x = int.Parse(y); // or x = Convert.ToInt32(y);

33. Java vs C#: Constants Java C# // May be initialized in a constructor
final double PI = 3.14;
const double PI = 3.14;
// Can be set to a const or a variable. //May be initialized in a constructor.
readonly int MAX_HEIGHT = 9;

34. Java vs C#: Operators Java C# Comparison == < > <= >= !=
== < > <= >= !=
Arithmetic
+ - * /
% (mod)
/ (integer division if both operands are ints)
Math.Pow(x, y)
Assignment
= += -= *= /= %= &= |= ^= <<= >>= >>>=
Bitwise
& | ^ ~ << >> >>>
= += -= *= /= %= &= |= ^= <<= >>=
& | ^ ~ << >>
^ XOR: The unsigned right shift operator ">>>" shifts a zero into the leftmost position, while the leftmost position after ">>" depends on sign extension.

35. Java vs C#: Operators Java C# Logical && || & | ^ !
&& || & | ^ !
Note: && and || perform short-circuit logical evaluations
String Concatenation +
Short-circuit: the second argument is only executed or evaluated if the first argument does not suffice to determine the value of the expression: when the first argument of the AND function evaluates to false, the overall value must be false; and when the first argument of the OR function evaluates to true, the overall value must be true.

36. CS 340
Questions?

37. Java vs C#: Choices Java C#
greeting = age < 20 ? "What's up?" : "Hello";
if (x < y)
System.out.println("greater");
if (x != 100) {
x *= 5;
y *= 2; }
else
z *= 6;
Console.WriteLine("greater");

38. Java vs C#: Choices Java C# int selection = 2; switch (selection) {
// Must be byte, short, int, char, or enum
case 1: x++;
// Falls through to next case if no break
case 2: y++; break;
case 3: z++; break;
default: other++; }
string color = "red";
switch (color) {
// Can be any predefined type
case "red": r++; break;
// break is mandatory; no fall-through
case "blue": b++; break;
case "green": g++; break;
default: other++; break;
// break necessary on default

39. Java vs C#: Loops Java C# while (i < 10) i++;
for (i = 2; i <= 10; i += 2)
System.out.println(i); do
while (i < 10);
for (int i : numArray) // foreach construct
sum += i;
Console.WriteLine(i);
foreach (int i in numArray)

40. Java vs C#: Loops Java C#
// for loop can be used to iterate through any Collection
import java.util.ArrayList;
ArrayList<Object> list = new ArrayList<Object>();
list.add(10); // boxing converts to instance of Integer
list.add("Bisons");
list.add(2.3); // boxing converts to instance of Double
for (Object o : list)
System.out.println(o);
// foreach can be used to iterate through any collection
using System.Collections;
ArrayList list = new ArrayList();
list.Add(10);
list.Add("Bisons");
list.Add(2.3);
foreach (Object o in list)
Console.WriteLine(o);

41. Java vs C#: Arrays Java C# int nums[] = {1, 2, 3}; or
for (int i = 0; i < nums.length; i++)
System.out.println(nums[i]);
String names[] = new String[5];
names[0] = "David";
float twoD[][] = new float[rows][cols];
twoD[2][0] = 4.5;
int[][] jagged = new int[3][];
jagged[0] = new int[5];
jagged[1] = new int[2];
jagged[2] = new int[3];
jagged[0][4] = 5;
for (int i = 0; i < nums.Length; i++)
Console.WriteLine(nums[i]);
string[] names = new string[5];
float[,] twoD = new float[rows, cols];
twoD[2,0] = 4.5f;
int[][] jagged = new int[3][] {
new int[5], new int[2], new int[3] };

42. Java vs C#: Functions Java C# // Return single value
int Add(int x, int y) {
return x + y; }
int sum = Add(2, 3);
// Return no value
void PrintSum(int x, int y) {
System.out.println(x + y);
PrintSum(2, 3);
Console.WriteLine(x + y);

43. Java vs C#: Functions Java C#
// Primitive types and references are always passed by value
void TestFunc(int x, Point p) {
x++;
p.x++; // Modifying property of the object
p = null; // Remove local reference to object }
class Point {
public int x, y;
Point p = new Point();
p.x = 2;
int a = 1;
TestFunc(a, p);
System.out.println(a + " " + p.x + " " + (p == null) ); // 1 3 false
// Pass by value (default), in/out-reference (ref), and out-reference (out)
void TestFunc(int x, ref int y, out int z, Point p1, ref Point p2) {
x++; y++; z = 5;
p1.x++; // Modifying property of the object
p1 = null; // Remove local reference to object
p2 = null; // Free the object
Point p1 = new Point();
Point p2 = new Point();
p1.x = 2;
int a = 1, b = 1, c; // Output param doesn't need initializing
TestFunc(a, ref b, out c, p1, ref p2);
Console.WriteLine("{0} {1} {2} {3} {4}",
a, b, c, p1.x, p2 == null); // True

44. Java vs C#: Functions Java C# // Accept variable number of arguments
int Sum(int ... nums) {
int sum = 0;
for (int i : nums)
sum += i;
return sum; }
int total = Sum(4, 3, 2, 1); // returns 10
int Sum(params int[] nums) {
foreach (int i in nums)

45. Java vs C#: Strings Java C# // String concatenation
String school = "Harding ";
school = school + "University"; // school is "Harding University"
// String comparison
String mascot = "Bisons";
if (mascot == "Bisons") // Not the correct way to do string comparisons
if (mascot.equals("Bisons")) // true
if (mascot.equalsIgnoreCase("BISONS")) // true
if (mascot.compareTo("Bisons") == 0) // true
System.out.println(mascot.substring(2, 5)); // Prints "son"
string school = "Harding ";
string mascot = "Bisons";
if (mascot == "Bisons") // true
if (mascot.Equals("Bisons")) // true
if (mascot.ToUpper().Equals("BISONS")) // true
if (mascot.CompareTo("Bisons") == 0) // true
Console.WriteLine(mascot.Substring(2, 3)); // Prints "son"

46. Java vs C#: Strings Java C# // My birthday: Oct 12, 1973
java.util.Calendar c = new java.util.GregorianCalendar(1973, 10, 12);
String s = String.format("My birthday: %1$tb %1$te, %1$tY", c);
// Mutable string
StringBuffer buffer = new StringBuffer("two ");
buffer.append("three ");
buffer.insert(0, "one ");
buffer.replace(4, 7, "TWO");
System.out.println(buffer); // Prints "one TWO three"
DateTime dt = new DateTime(1973, 10, 12);
string s = "My birthday: " + dt.ToString("MMM dd, yyyy");
System.Text.StringBuilder buffer = new System.Text.StringBuilder("two ");
buffer.Append("three ");
buffer.Insert(0, "one ");
buffer.Replace("two", "TWO");
Console.WriteLine(buffer); // Prints "one TWO three"

47. CS 340
Questions?

48. Java vs C#: Exception Handling
// Must be in a method that is declared to throw this exception
Exception ex = new Exception("Something is really wrong.");
throw ex;
try {
y = 0;
x = 10 / y;
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
// Code that always gets executed }
Exception up = new Exception("Something is really wrong.");
throw up; // ha ha
} catch (Exception ex) { // Variable "ex" is optional
Console.WriteLine(ex.Message);

49. Java vs C#: Namespaces Java C# package harding.compsci.graphics;
// Import single class
import harding.compsci.graphics.Rectangle;
// Import all classes
import harding.compsci.graphics.*;
namespace Harding.Compsci.Graphics {
... } or
namespace Harding {
namespace Compsci {
namespace Graphics {
using Rectangle = Harding.CompSci.Graphics.Rectangle;
// Import all class
using Harding.Compsci.Graphics;

50. Java vs C#: Classes / Interfaces
Accessibility keywords
public
private
protected
static
// Inheritance
class FootballGame extends Competition {
... }
internal
protected internal
class FootballGame : Competition {

51. Java vs C#: Classes / Interfaces
// Interface definition
interface IAlarmClock {
... }
// Extending an interface
interface IAlarmClock extends IClock {
// Interface implementation
class WristWatch implements IAlarmClock, ITimer {
interface IAlarmClock : IClock {
class WristWatch : IAlarmClock, ITimer {

52. Java vs C#: Constructors / Destructors
class SuperHero {
private int mPowerLevel;
public SuperHero() {
mPowerLevel = 0; }
public SuperHero(int powerLevel) {
this.mPowerLevel= powerLevel;
// No destructors, just override the finalize method
protected void finalize() throws Throwable {
super.finalize(); // Always call parent's finalizer
~SuperHero() {
// Destructor code to free unmanaged resources.
// Implicitly creates a Finalize method.

53. Java vs C#: Objects Java C# SuperHero hero = new SuperHero();
hero.setName("SpamMan");
hero.setPowerLevel(3);
hero.Defend("Laura Jones");
SuperHero.Rest(); // Calling static method
SuperHero hero2 = hero; // Both refer to same object
hero2.setName("WormWoman");
System.out.println(hero.getName()); // Prints WormWoman
hero = null; // Free the object
if (hero == null)
hero = new SuperHero();
Object obj = new SuperHero();
System.out.println("object's type: " + obj.getClass().toString());
if (obj instanceof SuperHero)
System.out.println("Is a SuperHero object.");
hero.Name = "SpamMan";
hero.PowerLevel = 3;
SuperHero.Rest(); // Calling static method
hero2.Name = "WormWoman";
Console.WriteLine(hero.Name); // Prints WormWoman
Console.WriteLine("object's type: " + obj.GetType().ToString());
if (obj is SuperHero)
Console.WriteLine("Is a SuperHero object.");

54. Java vs C#: Properties Java C# private int mSize;
public int getSize() { return mSize; }
public void setSize(int value) {
if (value < 0)
mSize = 0;
else
mSize = value; }
int s = shoe.getSize();
shoe.setSize(s+1);
public int Size {
get { return mSize; }
set {
shoe.Size++;

55. Java vs C#: Console I/O Java C#
java.io.DataInput in = new java.io.DataInputStream(System.in);
System.out.print("What is your name? ");
String name = in.readLine();
System.out.print("How old are you? ");
int age = Integer.parseInt(in.readLine());
System.out.println(name + " is " + age + " years old.");
int c = System.in.read(); // Read single char
System.out.println(c); // Prints 65 if user enters "A"
// The studio costs $ for 3 months.
System.out.printf("The %s costs $%.2f for %d months.%n", "studio", 499.0, 3);
// Today is 06/25/04
System.out.printf("Today is %tD\n", new java.util.Date());
Console.Write("What's your name? ");
string name = Console.ReadLine();
Console.Write("How old are you? ");
int age = Convert.ToInt32(Console.ReadLine());
Console.WriteLine(name + " is " + age + " years old.");
int c = Console.Read(); // Read single char
Console.WriteLine(c); // Prints 65 if user enters "A"
Console.WriteLine("The {0} costs {1:C} for {2} months.\n", "studio", 499.0, 3);
// Today is 06/25/2004
Console.WriteLine("Today is " + DateTime.Now.ToShortDateString());

56. Java vs C#: File I/O Java C# import java.io.*;
// Character stream writing
FileWriter writer = new FileWriter("c:\\myfile.txt");
writer.write("Out to file.\n");
writer.close();
// Character stream reading
FileReader reader = new FileReader("c:\\myfile.txt");
BufferedReader br = new BufferedReader(reader);
String line = br.readLine();
while (line != null) {
System.out.println(line);
line = br.readLine(); }
reader.close();
using System.IO;
StreamWriter writer = File.CreateText("c:\\myfile.txt");
writer.WriteLine("Out to file.");
writer.Close();
StreamReader reader = File.OpenText("c:\\myfile.txt");
string line = reader.ReadLine();
Console.WriteLine(line);
line = reader.ReadLine();
reader.Close();

57. CS 340
Questions?

58. CS440
References
C# versus Java : syntactic differences