Driving N on the Dalton Highway… (though it feels like it!)
Welcome to Programming Practicum
Waiting for the snow enveloping
you on Route 5 N to melt
“Putting the C into CS”
exploring
martian soil
On the 405, in traffic, being chased
by police (and TV) helicopters.
Pittsburgh
Victorville, for
DARPA's Urban
Granc Challenge
University of
St. Petersburg
DC for the
inauguration
Denver, CO or
Minneapolis, MN
You aren’t here
Worldcom
Headquarters
On fire just
W of here!!
Krispy Kreme’s
drive-through
writing clinic
reports
Waiting in line to
vote in the Florida
primaries…
rebooting
knuth (or
turing
or…)
coding
chunky
strings
Teaching Honors
English for Janice
Barbee at Pomona
High School
Being dragged off-course
18 miles into a marathon
race by a crazed spectator
clinic liaison
phone call
installing
Debian 3.1
Leading a Gray Davis /
Gary Coleman / Arnold
“T-800” Schwarzenegger
gubernatorial fundraiser
Massey University
Palmerston North, NZ
Mailing something at the
Claremont Post Office
the dumpster
Introductions!
Zach Dodds
Office
Olin 1255
Email dodds@cs.hmc.edu
fan of low-tech games
fan of low-level AI
ACM Jotto finale: Fall '08
Frosh
Sophs
Jrs
Srs
Others
pluto 0
pluto 2
pluto 3
pluto 1
pluto 1
andes 1
andes 1
andes 0
andes 2
andes 1
wired 1
wired 1
wired 1
wired 1
wired 0
xenon 1
xenon 1
xenon 1
xenon 1
xenon 0
tenet 1
tenet 0
tenet 0
tenet 3
tenet 0
clack 2
clack 1
clack 1
clack 0
clack 1
grime 1
grime 1
grime 1
grime 1
grime 0
these 0
these 1
these 0
these 4
these 1
flour 0
flour 2
flour 2
flour 1
flour 1
This set the record for the longest jotto game I've played at Mudd!
What is this course about?
What is this course about?
• A chance to “improve” your programming skills
What
Algorithm analysis and insight
Program design and implementation
optimizing
coding time
ACM programming contest
Why
Hands-on practice with algorithms and techniques
Familiarity with Java’s libraries OR your choice of language
Research/prototype programming
Unofficial course name: CS -70
"reasonable"
Last year's ACM
regional programming
contest
Aaron Pribadi,
Stuart
Persteiner, and
Daniel Lubarov
Anak Yodpinyanee
+ Jason
GarretGlaser
Kevin Oelze,
Andrew Hunter,
and Kwang
Ketcham
Marquis Wang,
Josh Ehrlich, and
Daniel Fielder
Class Organization
alternating format
discussion sessions
• problem and program analysis
• discussion of strategy and coding tips
• deciding on functional decomposition,
data structures, language facilities, and
algorithms to use in teams of 2-3
lab sessions
• teams may use 1 machine per
person (only the mock contest
adheres to ACM rules)
a team might want to
practice with only 1 machine
• these problems count for each
member of the group
• sometimes new problems, other times with known ones
• 3~ 4 problems given out per week…
Class Organization
Feedback from prior semesters…
• there should be an opportunity to start coding “cold”
• make individual vs. team-based work clear, lectures vs. labs
• problems are, in general, individually completed -- except
• those done during the lab "mock contest" sessions
• provide the code to all team members
• you may or may not choose to work as a team afterwards
• submit for each person (email me if there are problems…)
• problems per person per week?
• about 1~2 (if you work on a team in lab)
• and consider all of the weeks of the term!
• snacks and jotto!
• better support for newcomers and for contest problems!!
Course Organization
Sep 1
Sep 8
Sep 15
Sep 22
Sep 29
Oct 6
Oct 13
Oct 20
Oct 27
Nov 3
Nov 10
Welcome! Review? of dynamic programming: 3 problems
Lab/Mock contest session: 4 problems
Discussion session on graph problems: 3 problems
Lab/Mock contest session: 4 problems
Discussion session on geometry problems: 3 problems
Lab/Mock contest session: 4 problems
Discussion session on search problems: 3 problems
Mock ACM contest, 9pm – 1:00am, 6 problems
Lab/Mock contest session: 2 problems
Nov 7
Regional participants' -- preparation meeting
@ RCC
Discussion and wrap-up for the semester
You may submit problems until the end of exams…
Sat. Nov. 7 will be the regional contest
Course webpage
references
problem statements and sample data
problems you have solved
administrative info
Grading
CS 189 is graded individually... (it’s possible to take it P/F, too)
though not for CS elective credit…
Coding Guidelines
• problems can be done any time during the semester
• discussion of algorithms always OK
• coding should be within teams
• you may use any references except an existing solution
or partial solution…
• one person should take the lead on each problem
• use /cs/ACM/acmSubmit <file> to submit on knuth
• try things out !
the reason for ACM!
Problem credits
Problems are worth double if
• You solve them during the 4:15 - 5:30 lab sessions
the team gets credit, up to 3 people
• It's one of the "extra difficult" problems, which may be
determined as we go…
Language Choice?
• Any standard language is OK -- but do keep in mind
that the competition allows only Java, C, and C++ .
Other "standard" languages:
C#, Python, Ruby
somewhat reasonable alternatives will also be considered…
Problems are
also worth
double if they
are written up
for "the book."
A prior term's summary: languages
17
8
4
(+2)
16
1
6
20
3
1
(+2)
(+1)
(+1)
(+12)
(+1)
1
2
11
1
17
4
(+1)
(+1)
(+9)
(+2)
(+2)
2
2
8
3
8
(+2)
2
(+2)
13
14
(+10)
(+9)
1
21
1
1
(+16)
15
(+14)
(+4)
number of
2x scores
Tallies per problem and per
language (thus far)…
1
number of
4x scores
python 82
d
8
lua
2
java
60
ruby
6
awk
2
C++
40
scheme 3
js
2
1
each
sql
cobol
basic
x86 asm
pascal
mathematica
sh, latex
The "book"
Overheard at last fall's contest…
We will begin a multi-term effort
to create an HMC "book"
Problems contributed to the book
are worth triple, but
- need a thorough introductory explanation…
- need to be in Java or C++ (or C)
- need to be beautifully formatted
- need to be fully commented
- need to be useful for people who did not write it!
- variable names and other constructs ~ evident
Sign up for a problem if you want to do this.
(It's OK to work in a team of 2 or 3, as well.)
a secret weapon?
Dynamic programming?
No action shots?
Dynamic programming!
Excitement from the judges’ room
Excitement from the judges’ room
Backpacks not permitted…
Dynamic programming
When a seemingly intractable problem has lots of
repeated substructure, go DP!
Build a table of
partial results.
For example:
Replace computation with
table look-up when possible
Dynamic programming
When a seemingly intractable problem has lots of
repeated substructure, go DP!
Build a table of
partial results.
Replace computation with
table look-up when possible
the binary-decimal problem, for example:
2
6
3
19
0
Input
Numbers, N,
up to 106
0 marks the end of the input
Output
10
1110
111
11001
the smallest decimal
multiple of N with only
the digits 0 and 1 !
Ideas?
One way…
Count up to the solution,
starting from 1…
insight: from CS 60!
adding digits changes the error
(remainder) in predictable ways
Dynamic programming
Storing intermediate results in a table for fast look-up:
input N = 6
possible remainders upon dividing by N (6)
0
1
# of digits
in answer
2
3
4
1
2
3
4
5
Dynamic programming
Storing intermediate results in a table for fast look-up:
input N = 6
possible remainders upon dividing by N (6)
0
1
# of digits
in answer
2
3
4
1
1
2
3
4
5
Dynamic programming
Storing intermediate results in a table for fast look-up:
input N = 6
possible remainders upon dividing by N (6)
0
# of digits
in answer
1
1
1
2
1
3
4
2
3
4
5
10
11
Dynamic programming
Storing intermediate results in a table for fast look-up:
input N = 6
possible remainders upon dividing by N (6)
0
# of digits
in answer
1
1
1
2
1
3
1
4
2
110
3
111
4
5
10
11
10
11
Dynamic programming
Storing intermediate results in a table for fast look-up:
input N = 6
possible remainders upon dividing by N (6)
0
# of digits
in answer
1
2
3
4
5
10
11
1
1
2
1
3
1
110
111
10
11
1
110
111
10
11
4
1110
DP!
Only checking values for
which a remainder has
not yet been used…
Fast
Problem Set #0
(3-4 problems)
0-multiple, too!
In teams of 2~3, read over these…
Only students new to
ACM may do this one
for credit…
I need a picture of
Farmer Ran!
Problem Set #0
(3-4 problems)
In teams of 2~3, read over these & discuss:
• How difficult are they? Which might be DP?
• Where might the structure of the problem depend on
similar (but smaller!) substructure?
• How might you build up a table of values toward an
overall solution?
• Think of your class's next 5-letter jotto word or guess… !
Jotto!
A word-guessing game similar to mastermind…
Sophs
Jrs
Srs
Profs
pluot 1
pluot 1
pluot 0
pluot 0
pluot 1
pluot 1
pluot 2
pluot 2
Next Tuesday: Lab
bring a laptop, if you have one…
Another example
binary-as-decimal
problem
"pebbles" problem
(2007 ACM regionals)
Input
3
7
4
8
9
6
6
1
1
Square array, up to
15x15, of integers
from 1 to 99
Idea
3
7
4
8
9
6
6
1
1
place "pebbles" on integers, trying
to maximize total, but no two
pebbles may be adjacent…
vertically, horizontally, or diagonally
maximum
possible sum
14?
Output
naïve running time?
Pebbles
DP Idea
consider all possibilities for pebbling each row they only depend on the previous row's best scores!
Subset chosen (pebbles)
000
Input
8
9
6b
6
1
1c
Square array, up to
15x15, of integers
from 1 to 99
010
011
100
101
110
0
Row #
3
7
4a
001
1
2
Store the BEST score available for each possible subset.
111
Pebbles
DP Idea
consider all possibilities for pebbling each row they only depend on the previous row's best scores!
Subset chosen (pebbles)
Input
8
9
6b
6
1
1c
Square array, up to
15x15, of integers
from 1 to 99
Row #
3
7
4a
0
000
001
010
011
100
101
110
111
0
6
8
x
3
9
x
x
1
2
Store the BEST score available for each possible subset.
Pebbles
DP Idea
consider all possibilities for pebbling each row they only depend on the previous row's best scores!
Subset chosen (pebbles)
000
001
010
011
100
101
110
111
0
0
6
8
x
3
9
x
x
1
0+9
1+3
9+0
7+6
8+0
x
x
3
7
4a
8
9
6b
6
1
1c
Square array, up to
15x15, of integers
from 1 to 99
Row #
Input
9
4
9
x
13
8
2
Store the BEST score available for each possible subset.
Pebbles
DP Idea
consider all possibilities for pebbling each row they only depend on the previous row's best scores!
Subset chosen (pebbles)
000
001
010
011
100
101
110
111
0
0
6
8
x
3
9
x
x
1
0+9
1+3
9+0
2
0+13
c+13
3
7
4a
8
9
6b
6
1
1c
Row #
Input
9
4
9
x
7+6
13
8+0
8
x
x
b+9
x
a+9
?
x
x
Store the BEST score available for each possible subset.
Square array, up to
15x15, of integers
from 1 to 99
What is the best here?
running time?
Pebbles
binary-as-decimal
problem
"pebbles" problem
(2007 ACM regionals)
Input
71
85
92
23
64
24
50
96
61
33
95
74
23
31
32
56
94
71
30
95
Square array, up to
15x15, of integers
from 1 to 99
54
28
10
46
89
Idea
71
85
92
23
64
24
50
96
61
33
95
74
23
31
32
56
94
71
30
95
54
28
10
46
89
place "pebbles" on integers, trying
to maximize total, but no two
pebbles may be adjacent…
maximum
possible sum
572
Output
code
Scanner sc = new Scanner(System.in);
even a bit easier!
This sure is sum code…
to the max
Martijn is VERY shifty!
Martijn is shifty!
Where is the table?
Thanks, Martijn!
Jotto!
A word-guessing game similar to mastermind…
Sophs
Jrs
Srs
Me
pluot 1
pluot 0
pluot 1
pluot 2
Problem Set #1
Input
4 4
tow
cat
row
care
...
.#.
...
.##
0 0
(6 probs, 3 wks)
# of words in the puzzle (to follow)
# of rows in the puzzle (after the words)
the words
the puzzle
this indicates the end of the input…
Problem Set #1
(6 probs, 3 wks)
Input
4 4
tow
cat
row
care
...
.#.
...
.##
0 0
Problem 1
either the solution OR a
cat
statement that it can't be
solved…
a#o
row
e##
Problem 2:
no layout is possible.
Output
Problem Set #1
Input
6 5
1
# of empty boxes on the form
# of clerks in the office (three lines each)
the box(es) CHECKED
clerk #0
the box(es) ERASED
1 2
2 3
4
4
5
1
3
2
(6 probs, 3 wks)
the clerks who get a copy
clerk #1
0
1
2
3
5
the
form
clerk #2
clerk #3
1
4
2
1 0
0 0
4
clerk #4
this indicates the end of the input…
Problem Set #1
Input
6 5
1
# of empty boxes on the form
# of clerks in the office (three lines each)
the box(es) CHECKED
clerk #0
the box(es) ERASED
1 2
2 3
4
4
5
1
3
2
(6 probs, 3 wks)
the clerks who get a copy
clerk #1
0
1
2
3
5
the
form
clerk #2
let's try it…
clerk #3
1
4
2
1 0
0 0
4
clerk #4
this indicates the end of the input…
Problem Set #1
Input
6 5
1
# of empty boxes on the form
# of clerks in the office (three lines each)
the box(es) CHECKED
clerk #0
the box(es) ERASED
1 2
2 3
4
4
5
1
3
2
(6 probs, 3 wks)
the clerks who get a copy
clerk #1
0
1
2
3
4
5
the
form
clerk #2
clerk #3
1
4
2
1 0
0 0
1 3 4 5
clerk #4
Output
the boxes checked the last time it leaves
clerk #0's desk…
this indicates the end of the input…
Problem Set #1
Input
(6 probs, 3 wks)
list of traits, R == "recessive" D == "dominant"
D traits are passed if EITHER parent has them
RDDR
Speedy M 0101
Jumper F 0101
Slowpoke M 1101
Terror F 1100
Shadow F 1001
***
Frisky 0101
Sleepy 1101
***
R traits are passed if BOTH parents have them
all of the parents, gender, and traits
the baby shrews…
Deduce their possible parents!
Problem Set #1
Input
(6 probs, 3 wks)
list of traits, R == "recessive" D == "dominant"
D traits are passed if EITHER parent has them
RDDR
Speedy M 0101
Jumper F 0101
Slowpoke M 1101
Terror F 1100
Shadow F 1001
***
Frisky 0101
Sleepy 1101
***
R traits are passed if BOTH parents have them
all of the parents, gender, and traits
the baby bunnies…
Deduce their possible parents!
Frisky by Jumper-Slowpoke or Jumper-Speedy or ______
Sleepy by _________
Output
Problem Set #1
Input
(6 probs, 3 wks)
list of traits, R == "recessive" D == "dominant"
D traits are passed if EITHER parent has them
RDDR
Speedy M 0101
Jumper F 0101
Slowpoke M 1101
Terror F 1100
Shadow F 1001
***
Frisky 0101
Sleepy 1101
***
R traits are passed if BOTH parents have them
all of the parents, gender, and traits
the baby bunnies…
Deduce their possible parents!
Frisky by Jumper-Slowpoke or Jumper-Speedyor
Sleepy by Shadow-Slowpoke
Shadow-Speedy
Output
Problem Set #1
(6 probs, 3 wks)
Read these three problems… then
Decide which problem is the easiest
and which one is the hardest …
(to code, not to compute!)
Problem Set #1
my estimates…
hardest
easiest
(6 probs, 3 wks)
important heuristic:
I’m always wrong
See you next Tuesday
in the CS labs… !
Driving N on the Dalton Highway… (though it feels like it!)
Welcome to Programming Practicum
Waiting for the snow enveloping
you on Route 5 N to melt
“Putting the C into CS”
Pittsburgh
University of
St. Petersburg
Engineering dept.
exploring
martian soil
On the 405, in traffic, being chased
by police (and TV) helicopters.
You aren’t here
Worldcom
Headquarters
Krispy Kreme’s
drive through
writing clinic
reports
rebooting
knuth (or
turing
or…)
coding
chunky
strings
Teaching Honors
English for Janice
Barbee at Pomona
High School
Being dragged off-course
18 miles into a marathon
race by a crazed spectator
clinic liaison
phone call
installing
Debian 3.1
Leading a Gray Davis /
Gary Coleman / Arnold
“T-800” Schwarzenegger
gubernatorial fundraiser
Massey University
Palmerston North, NZ
Mailing something at the
Claremont Post Office
the dumpster
What is this course about?
• A chance to “improve” your programming skills
What
Algorithm analysis and insight
Program design and implementation
optimizing
coding time
ACM programming contest
Why
Hands-on practice with algorithms and techniques
Familiarity with Java’s libraries OR your choice of language
Research/prototype programming
Unofficial course name: CS -70
1-4 / team
3 per team
2/team
2 per team
Course Organization
Jan 16
Jan 23
Jan 30
Feb 6
Feb 13
Feb 20
Feb 27
Mar 6
Mar 20
Mar 27
Apr 3
Welcome! Random teams of 3: 6 problems, 3 weeks
Lab session to work on problems (Beckman B102 or 105)
Discussion session on the first set of problems
Lab session with new problems: 4 problems, 2 weeks
Discussion session on the second set of problems
Lab session with new problems: 6 problems, 3 weeks
Discussion session on the third set of problems
No class - Fall break
Mock ACM contest, 9pm – 1am, teams of 3, 6 pr, 4 hours
No class (out of town)
Discussion session on the mock contest + Finale!
You may submit problems until the end of exams…
Class Organization
alternating format
discussion sessions
• problem and program analysis
• discussion of strategy and coding tips
• deciding on functional decomposition,
data structures, language facilities, and
algorithms to use in teams of 2-3
lab sessions
• teams should use 1 terminal
per person (only the mock
contest adheres to ACM rules)
• these problems count for each
member of the group
• sometimes new problems, other times with known ones
• ~1 problem per week per person…
Course webpage
reference links
problem statements
and test data
problems your team
has solved
administrative info
Grading
CS 189 is graded individually... (it’s possible to take it P/F, too)
Coding Guidelines
• problems can be done any time during the semester
• discussion of algorithms always OK
• coding should be within teams
• you may use any references except an existing
solution or partial solution…
• one person should take the lead on each problem
• use /cs/ACM/acmSubmit <file> to submit
• try things out !
the reason for ACM!
Choose your language…
Java is almost the universal choice for the competition…
• extensive library of data structures and algorithms available
• I/O made simpler with 1.5’s Scanner and printf
Input from stdin
Output to stdout
the C in CS!
Choose your language…
Python is nice
C#
Whatever language you choose
def floyd_warshall(W, infinity):
needs to be able to run on the
n = matrix.get_num_rows(W)
Macs in the CS labs (and
D = matrix.clone(W)
DD = matrix.make(n,n)
preferably knuth, as well…)
for k in xrange(n):
for i in xrange(n):
for j in xrange(n):
DD[i][j] = min(D[i][j], D[i][k] + D[k][j])
DD, D = D, DD
return D
I’ll likely need your help to get
things set up for testing…
Others ?
Marty: prolog!
Problem Set #1
Input
4 4
tow
cat
row
care
...
.#.
...
.##
0 0
(6 probs, 3 wks)
# of words in the puzzle (to follow)
# of rows in the puzzle (after the words)
the words
the puzzle
this indicates the end of the input…
Problem Set #1
Input
6 5
1
# of empty boxes on the form
# of clerks in the office (three lines each)
the box(es) CHECKED
clerk #0
the box(es) ERASED
1 2
2 3
4
4
5
1
3
2
(6 probs, 3 wks)
the clerks who get a copy
clerk #1
0
1
2
3
4
5
the
form
clerk #2
clerk #3
1
4
2
1 0
0 0
1 3 4 5
clerk #4
Output
the boxes checked the last time it leaves
clerk #0's desk…
this indicates the end of the input…
Problem Set #1
Input
(6 probs, 3 wks)
list of traits, R == "recessive" D == "dominant"
D traits are passed if EITHER parent has them
RDDR
Speedy M 0101
Jumper F 0101
Slowpoke M 1101
Terror F 1100
Shadow F 1001
***
Frisky 0101
Sleepy 1101
***
R traits are passed if BOTH parents have them
all of the parents, gender, and traits
the baby shrews…
Deduce their possible parents!
Frisky by Jumper-Slowpoke or Jumper-Speedy or ______
Sleepy by _________
Output
Problem Set #1
(6 probs, 3 wks)
Read these three problems… then
Decide which problem is the easiest
and which one is the hardest …
(to code, not to compute!)
Coaches’ Room
Choose your language…
Java/Cthe universal choice for the competition…
• extensive library of data structures and algorithms available
• I/O made simpler with 1.5’s Scanner and printf
Input from stdin
Output to stdout
the C in CS!
Choose your language…
Python is nice
def floyd_warshall(W, infinity):
n = matrix.get_num_rows(W)
D = matrix.clone(W)
DD = matrix.make(n,n)
for k in xrange(n):
for i in xrange(n):
for j in xrange(n):
DD[i][j] = min(D[i][j],
D[i][k] + D[k][j])
DD, D = D, DD
return D
Postscript!
Ruby :-)
Marty: prolog!
Driving N on the Dalton Highway… (though it feels like it!)
Welcome to Programming Practicum
Waiting for the snow enveloping
you on Route 5 N to melt
“Putting the C into CS”
Pittsburgh
Victorville, for
DARPA's Urban
Granc Challenge
University of
St. Petersburg
Engineering dept.
exploring
martian soil
On the 405, in traffic, being chased
by police (and TV) helicopters.
You aren’t here
Worldcom
Headquarters
Krispy Kreme’s
drive-through
writing clinic
reports
Waiting in line to
vote in the Florida
primaries…
rebooting
knuth (or
turing
or…)
coding
chunky
strings
Teaching Honors
English for Janice
Barbee at Pomona
High School
Waiting in line to
vote in the Florida
primaries…
Being dragged off-course
18 miles into a marathon
race by a crazed spectator
clinic liaison
phone call
installing
Debian 3.1
Leading a Gray Davis /
Gary Coleman / Arnold
“T-800” Schwarzenegger
gubernatorial fundraiser
Massey University
Palmerston North, NZ
Mailing something at the
Claremont Post Office
the dumpster
What is this course about?
• A chance to “improve” your programming skills
What
Algorithm analysis and insight
Program design and implementation
optimizing
coding time
ACM programming contest
Why
Hands-on practice with algorithms and techniques
Familiarity with Java’s libraries OR your choice of language
Research/prototype programming
Unofficial course name: CS -70
Class Organization
alternating format
discussion sessions
• problem and program analysis
• discussion of strategy and coding tips
• deciding on functional decomposition,
data structures, language facilities, and
algorithms to use in teams of 2-3
lab sessions
• teams should use 1 machine
per person (only the mock
contest adheres to ACM rules)
• these problems count for each
member of the group
• sometimes new problems, other times with known ones
• ~3 problems per week per person…
Class Organization
Feedback from prior semesters…
• there should be an opportunity to start coding “cold”
• make individual vs. team-based work clear, lectures vs. labs
• problems are, in general, individually completed, except
• those done during the lab "mock contest" sessions
• provide the code to all team members
• you may or may not choose to work as a team afterwards
• submit for each person (or email me…)
• problems per person per week?
• ~2 in the fall
• ~3 in the spring
• snacks and jotto!
Course Organization
Jan 29
Feb 5
Feb 12
Feb 19
Feb 26
Mar 4
Mar 11
Mar 18
Mar 23
Mar 25
Welcome! Review of dynamic programming: 4 problems
Lab/Mock contest session: 4 problems
Discussion session on geometry problems: 4 problems
Lab/Mock contest session: 4 problems
Lab/Mock contest session: 4 problems
Discussion session on search problems: 4 problems
No class… need to be away
No class - Spring break
Mock ACM contest, 9pm – midnight, 6 problems
Discussion and wrap-up of the semester
You may submit problems
until the end of exams…
Sat. Mar 8 and Sat. Apr 19
external competitions…
Competition Options
www.ccsc.org/southwestern/2008/contest.html
Sat. Mar 8 and Sat. Apr 19
external competitions…
www.ieee.org/web/membership/students/scholarshipsawardscontests/ieeextreme.html
Course webpage
references
problem statements and test data
problems you have solved
administrative info
Grading
CS 189 is graded individually... (it’s possible to take it P/F, too)
Coding Guidelines
• problems can be done any time during the semester
• discussion of algorithms always OK
• coding should be within teams
• you may use any references except an existing
solution or partial solution…
• one person should take the lead on each problem
• use /cs/ACM/acmSubmit <file> to submit
• try things out !
the reason for ACM!
Problem multipliers
Problems are worth double if
• You solve them during the 4:15 - 5:30 lab sessions
the team gets credit, up to 3 people
• You are the first person to use a particular language
- though there is an additional responsibility here: to
set up the testing system to handle that language!
languages already used:
python 56
c++
11
c#
ruby 12
perl
2
haskell 1
java
postscript 2
6
prolog
• It's one of the "extra difficult" problems, which will
be determined as we go…
8
c
5
php
1
2
These multipliers may
be accumulated…
Dynamic programming
When a seemingly intractable problem has large amounts of repeated or
redundant substructure, DP can sometimes provide an efficient solution.
Build a table of
partial results.
For example:
2
6
3
19
0
Replace computation with
table look-up when possible
Output
Input
Numbers, N,
up to 106
0 marks the end of the input
10
1110
111
11001
the smallest decimal
multiple of N with only
the digits 0 and 1 !
Ideas?
One way…
Count up to the solution,
starting from 1…
Dynamic programming
Storing intermediate results in a table for fast look-up:
input N = 6
possible remainders upon dividing by N (6)
0
# of digits
in answer
1
2
3
4
5
10
11
1
1
2
1
3
1
110
111
10
11
1
110
111
10
11
4
1110
DP!
Only checking values for
which a remainder has
not yet been used…
Problem Set #1
(4 problems)
- divide up with one problem per group -
In teams of ~3, think about
- how would you solve this problem?
- is it a dynamic programming problem?
- how could you most simplify the programming ?
- think of a 5-letter jotto word… !
Competition Options
www.ccsc.org/southwestern/2008/contest.html
Sat. Mar 8 and Sat. Apr 19
external competitions…
www.ieee.org/web/membership/students/scholarshipsawardscontests/ieeextreme.html