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Electrical Engineering UET Lahore (2001-2005) ... Find 3 hotels closest to Islamabad Airport. A Brute Force Solution. Algorithm: ... – PowerPoint PPT presentation

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Title: Outline

1
Outline
• Who am I?
• What is research?
• My Research
• Higher studies opportunities in Australia
• Getting jobs in IT industry
• Presented by
• Muhammad Aamir Cheema, Lecturer IT at James Cook
University Australia, Sydney campus

2
Who Am I? A Student
• BSc. Electrical Engineering UET Lahore
(2001-2005)
• Masters by research University of New South Wales
(UNSW) Sydney (2005-2007)
• Currently a PhD Student at UNSW Sydney
• Research Area Databases

3
Who Am I? A Teacher
• Tutor _at_ University of New South Wales, Sydney
• Lecturer IT _at_ James Cook University Sydney Campus
• Courses Taught
• Database Systems Implementation
• Database Systems
• Operating Systems and Architectures
• Portable Programming
• C

4
What is Research?
• Formally a form of systematic enquiry that
contributes to knowledge.
• Is research boring and difficult???
• NOT AT ALL if you like solving puzzles
• Informally,
• Research Solving Puzzles

5
Lets Play a Game1
• Task Find the missing number
• Given Data set consists of numbers from 1 to
20
• Version 1
• Numbers are not displayed on the screen
• Version 2
• Find the missing number from the list below
• 4,2,8,18,1,20,17,9,16,15,13,3
,12,19,6,5,14,7,10
• Version 1 is more difficult because
• No element can be seen twice
• We cannot memorize all the numbers

1- Data Streams Algorithms and Applications, S.
Muthukrishnan
6
Brute Force Solution for Version 2
• 4,2,8,1,10,9,5,3,6
• Is 1 missing?
• Is 2 missing?
• Is 3 missing? . . .
• Algorithm
• For each number i from 1 to n
• Check whether i is missing or not
• Performance
• Space Usage (n-1) elements ? O(n)
• Running Time O(n2)

7
Sorting A faster solution
• 4,2,8,1,10,9,5,3,6
• 1,2,3,4,5,6,8,9,10
• Sort the numbers
• Scan the list to find missing number
• Performance
• Space Storage O(n)
• Running Time sorting time final scan
• nlogn n ? O(nlogn)

8
Bucket Even faster approach
• 4,2,8,1,10,9,5,3,6
• Algorithm
• create an empty array of size n
• For each element i in the list
• Mark the element at index i
• Unmarked index is the missing number
• Performance
• Space Requirement O(n)
• Running Time O(n)

9
Solution for Version 1???
• What we have done so far
• Developed solution for Version 2
• Performance Space Usage O(n)
• Running Time O(n)
• Version 1
• A solution is required that
• Accesses each element only once Running Time
O(n)
• Memorizes only one number Space Usage
O(1)
• An example application data passing through a
network node (e.g a router cannot store all the
data passing through it and can see each element
only once)

10
Hint
• Given numbers are from 1 to 10
• Task Nine numbers from the data are sent to user
one by one, find the missing number
• Sum of the numbers from 1 to 10 is 55

11
Solution
• Given Numbers are from 1 to n
• Algorithm
• Find the sum of 1 to n numbers? Sn(n1)/2
• For each number i
• SS-i
• S is missing number
• Performance
• Space Usage O(1)
• Running Time O(n)

12
My Research
• Nearest Neighbors Problem
• Given a set of objects O, find k objects closest
to any given query object
• Objects are represented by their location
coordinates
• Applications
• Find 5 taxis nearest to my current location
• Find 3 hotels closest to Islamabad Airport

13
A Brute Force Solution
• Algorithm
• Let q be the query object
• For each object x
• Find the distance of x from q
• Report the k objects with the minimum distance
from q

14
Problems with the brute force approach
• Distance of all objects from the query object is
to be calculated Running Time O(n)
• What if all the objects are moving (e.g cars on a
• To update the results, compute distance of all
objects again

15
A better solution
• Compute the distance of only the objects in
vicinity of the query object q
• How to find the objects that lie in vicinity of
q?
• Use some spatial Index. i.e grid index

16
CircularTrip1
• Explore the objects around q in an iteratively
increased circle
• Use grid based index (visit the cells around q
that intersect the circle)

p1
q
r
p2
• 1- Muhammad Aamir Cheema, Yidong Yuan, Xuemin
Lin, "CircularTrip An Effective Algorithm for
Continuous kNN Queries", DASFAA 2007, Thailand.

17
Updating the result on movement of objects
• Incoming objects any non-result object p
entering inside the circle
• Insert p into answer list
• Outgoing objects any result object leaving the
circle
• delete p from answer list
• Hanlde all the object updates as mentioned above
• Case 1 answer list contains k or more than k
objects
• Keep k closest objects and discard other
• Case 2 answer list contains less than k objects
• Same as initial computation except the starting

p1
q
distk
p2
18
Higher Studies Opportunities in Australia
• Student Visa
• Apply in any institution you like
• Take IELTS exam (you need 6 band overall)
• Show bank statement
• Permanent Visa
• Get three year work experience in Pakistan
• Take IELTS (minimum 7 band in each module)
• Apply for Permanent residence (PR) visa
• Go there and get education with benefits of being
a citizen of Australia (e.g more scholarship
opportunities, HEC loan etc)

19
Higher studies opportunities in Australia
• Student Visa
• Quick (you will not need to wait to complete 3
yrs work experience to get PR)
• You become eligible for PR once you complete your
degree (duration must be at least 2 years) in
Australia
• Permanent Visa
• Less expensive (once you are citizen your
chances of getting scholarship grow enormously)

20
When Australia?
• Education in Australia is not cheap but Australia
is accomodating
• Prefer European countries or try HEC scholarships
if you are not interested in settling abroad

21
Getting Jobs in IT industry
• University degrees teach you little bit of
everything
• A regular student becomes Jack of all trades but
master of none
• To get good jobs, you must become Jack of all