Download Sept 2 - Joshua Stough

CSCI 62
Data Structures
Dr. Joshua Stough
September 2, 2008
About CSCI 62
•
•
•
•
Abstract Data Types
Inheritance, interfaces – adv programming
Algorithms – efficiency (space, time)
Move to C++
• Is CSCI 62 right for you?
• Requirements / prerequisites
– CSCI 51, or substantial AP course
Course Web Pages
• Sakai system login:
– https://sakai.claremont.edu
• ~jstough/teaching/CS62F08/CS62F08
.html
• Course Documents
• Assignments
• Checking Grades
How to get access
• Not a CMC student: see Bruce Frost at Bauer 21
(that is this building) and get your computer account
set up. The process takes about five minutes or so.
You MUST have an account set up to be able to hand
in your homework assignments electronically.
• After-hour access into Adams for non-CMC students Need to activate your card for the card reader - do
the following: fill out the list being circulated.
• When the paper work is done, you will be asked to go
to Story House (building immediately south of Collins
Dining Hall) to get your card activated.
Lecture Format
• Review previous material
– questions
• Present new material
• In-class exercises
• Lecture notes will be posted, but may be
modified shortly after lecture.
Office Hours and Tutors
• M 4PM, W 3PM-on, F 3PM. All 2nd Adams.
• Anytime I am in Collins.
• Please come to office hours.
Software
• Java SDK.
• Eclipse
– on public lab machines
• http://www.claremontmckenna.edu/its/StudentG
uide/Labs/default.php
• you can install on your machine
• After-hours access
– Email Patrice Tonnis, [email protected], and request
card activation.
Grades
• Assignments
40%
– both programs and book
• Midterms
20%
• Final
30%
• Attendance and
Participation
10%
_____________________
• Total
100%
Assignments
• Please submit electronic copies by 11:59PM
on the due date.
– turn in using Sakai dropbox
• Homework assignments
– practice for exams
• Programming assignments
– budget 10-15 hours per program
• design, code, debugging
– start early!
Submitting Assignments
• All assignments will be submitted through
Sakai drop box.
• Submission Errors
– I will email you and give a deadline for re-submitting
– not checking your email is not an excuse for missing
the deadline
Late Policy
• Late Assignments lose 10, 15, 25, 25, 25% for each additional
day late (no credit on the fifth day). This scale may be delayed
given the severity of your circumstances and my being
informed of them in a timely manner.
• I will defer to the Counseling Center (see
http://www.cuc.claremont.edu/counseling).
• If you have an athletic event and will not be able to make a
deadline, you should tell me within a day of an assignment
being posted.
Approaching an assignment
• Before you open eclipse and start coding
(and asking for help):
–
–
–
–
read the assignment
think about what the assignment is asking for
review lectures and examples on the topic
write (yes, on paper) your plan for completing the
assignment (i.e., your algorithm)
• talk to/email me if you’re having trouble at this point
Backup Your Work!
• Backup your work!
• You will lose something at some point
– you might have to learn the hard way
• Use your U: drive
• 607-0911
Collaborating
• You should
– Struggle with the material before seeking
help.
– Come to office hours, email me.
– Make sure you understand the solutions
you receive help on, whether from fellow
students or me.
Sending Email to me
• Put CSCI 62 in subject line
• For example:
– CSCI 62, I’m lost
– CSCI 62, This course is too easy
Eclipse and Java
• http://www.eclipse.org/downloads/
– Eclipse IDE for Java Developers (85 MB)
– Or download from the course schedule.
• http://www.java.com/en/download/
Abstract Data Types
• Data structures are for the efficient
storage, retrieval and manipulation of
data.
Linked Lists
• Three classes (typically) working together
– an “item” class
• one atomic unit of the aggregate data
• e.g., a “Name” class (item) might have two instance
variables
String first, last;
– a “node” class
• one “item” and a reference to the next “node”
• the next reference is the “link” in “linked list”
– a “list” class
• reference to the first “node”—head of the list
Linked Lists
List
Item
data
Node
Item
nextNode
head
Node
Node
Node
Node
Node
Node
Linked Lists
New
List
head
Node
Node
Node
Node
Node
Node
List
head
Node
Node
Node
Node
Node
Node
Node
Linked Lists
Find
List
head
Node
Node
Node
Node
Node
Node
Linked Lists
Insert
List
head
Node
Node
Node
Node
Node
Node
Node
Linked Lists
Delete
List
head
Node
Node
Node
Node
Node
Node
Stacks
• Like a stack of paper (or cafeteria trays)
– “last-in first-out” (LIFO)
• can only add to the top - push
• can only remove from the top - pop
• Why?
– Often used to keep track of execution in a program
• when returning from a method call, the computer has to
remember where it last was
Stack
Stack
top
Node
Node
Node
Node
Node
Node
May be implemented as
a linked list
Only have access to the
top of the stack
Queues
• Standing in line
– “first-in first-out” (FIFO)
• add to the “tail” of the list (back of line) - enqueue
• remove from the “head” (head of line) - dequeue
• Why?
– often used to keep things in the order that they
arrived
– processes to be scheduled on the CPU
– packets arriving to a router
Queue
Queue
head
Node
Node
Node
Node
Node
Node
tail
May be implemented as
a linked list
Only have access to the
head and tail of the
queue
Trees
• Nodes can have more than one link
• Links are bi-directional
– forward link points to children
– backward link points to parent
• Why?
– keeping items in sorted order
• easy to add things in sorted order
– fast search
– also often used to parse arithmetic expressions
(order of operations)
Binary Trees
• Every node has a
parent, except head
root
• Every node has at
most two children
• root - has no parent
• leaf - has no children
leaves
Binary Trees
And Expressions
(3 + 2) * 5
Called a parse tree
3+2*5
+
*
+
3
5
2
3
*
2
Evaluate deepest expressions first.
5
Binary Search Tree
• The first item added
is the root
• Items less than the
root go on the left
branch
• Items greater than
the root go on the
right branch
• Makes searches
very efficient
3
1
5
4
7
possible order added:
31547
31574
35174
35147
Move to C++
// In C++
#include <iostream>
using namespace std;
int main () {
cout << "Welcome to C++";
return 0;
}
// In Java
public class Hello {
public static void main(String[]args)
{
System.out.println("Welcome to Java");
}
}