Navigation Menu

• Home
• Articles
• Work
• My Stuff
• Links
• About
• Contact

DWITE

DWITE is an online programming contest based in Ontario, Canada. It is a practice contest with 5 rounds in a year, all held before other real contests. (For example, ECOO and CCC begin in March.) Its official web site is http://www.dwite.ca/.

My solutions are in Java, requiring version 5.0 or above. Using an editor with syntax highlighting is highly recommended.

Trivia: DWITE stands for Do While If Then Else.

Problems and solutions

Contest date	Problem	Solution	Comments
2004-10	#1	Area of Circle	Trivial.
	#2	24 Hour Clock	Trivial.
	#3	The Tallest in the Class	Straightforward: Sorting.
	#4	CD-ROM Files	Subset sum problem (dynamic programming).
	#5	Super Long Sums	Trivial, using java.math.BigInteger.
2004-11	#1	Credit Card Check Digit	Trivial.
	#2	Squareland	Trivial.
	#3	Factoring	Rational zeros of polynomials.
	#4	For Loops	Dijkstra’s shunting yard algorithm.
	#5	Wind Chill	Trivial.
2004-12	#1	Prime Factorization	Recursion, primality testing.
	#2	Squareland II	Straightforward. Can be sped up from O(n4) to O(n2) by dynamic programming, though.
	#3	Reflections	Trivial: Trigonometry.
	#4	Waring’s Prime Number Conjecture	Brute force search with help from the Sieve of Eratosthenes.
	#5	Hidden Geography	Trivial: String processing and searching.
2005-01	#1	DWITE Golf Tournament	Straightforward: Sorting.
	#2	Minesweeper	Straightforward.
	#3	Harshad Numbers	Straightforward, using brute force search.
	#4	Zeller’s Congruence	Trivial: Follow the given algorithm.
	#5	Different Bases Multiplication	Trivial.
2005-02	#1	Bretschneider’s Formula	Trivial.
	#2	Snakes	Flood fill and neighbour count.
	#3	Simple Continued Fractions	Trivial.
	#4	Matrix Chain Product	Matrix chain multiplication (dynamic programming).
	#5	Tsunami Speed	Trivial.
2005-10	#1	Odometers	Mine runs in O(n2) time, where n is the number of digits. The O(10n) solution is straightforward.
	#2	The Game of Life	Straightforward.
	#3	Sum ’Em Up	Trivial, and the sum can be written in closed form.
	#4	Minesweeper	Flood fill (recursion).
	#5	Five Digit Divisibility	Brute force search through all permutations.
2005-11	#1	Quadrilateral Centroid	Trivial, arithmetic mean.
	#2	Variations on the Game of Life	Straightforward.
	#3	Cinquain Poetry	Trivial.
	#4	Stacking Blocks	Subset sum problem (dynamic programming).
	#5	Base64 Encoding	Straightforward.
2005-12	#1	Semiprimes	Straightforward.
	#2	The Maze	Breadth-first search, and the problem is plagiarized from DWITE 2003-10 #5.
	#3	Reducing Fractions	Straightforward: GCD algorithm.
	#4	Now I Know My ABC’s	Trivial: Histogram.
	#5	How Many Sums	Subset sum problem (dynamic programming).
2006-01	#1	Filling The Cone	Trivial: Algebra.
	#2	Scrabble	Straightforward but long.
	#3	London Knights	Straightforward: Sorting. It screams for the use of SQL, though.
	#4	Equivalent Amounts	Trivial. Convert to common unit, then convert from common unit.
	#5	Distance Between Towns	Dijkstra’s algorithm.
2006-02	#1	Points on a Line	Trivial. Mine doesn’t use the division operation.
	#2	Floppy Disk 3½-inch High Density	Subset sum problem (dynamic programming).
	#3	UPC Check Digit	Trivial.
	#4	Connect-4	Straightforward.
	#5	Prime Palindromes	Straightforward: Brute force search, Sieve of Eratosthenes.
2006-10	#1	Pete’s Printing Press	Trivial, but the data table is large.
	#2	Body Mass Index	Trivial.
	#3	Basketball Statistics II	Straightforward: Sorting.
	#4	Count Squares	Straightforward. Can be sped up from O(n5/2) to O(n3/2) using dynamic programming, where n is the number of cells.
	#5	Bad Input II	Trivial if you have access to a bignum library.
2006-11	#1	13375P34|<	Trivial.
	#2	Lottery Ticket Checker	Trivial.
	#3	Linear Binomial Products	Straightforward.
	#4	Money Prize	Dynamic programming.
	#5	Goldbach’s Weak Conjecture	Recursion, Sieve of Eratosthenes.
2006-12	#1	Jimmy’s Lost His Marbles	Subset sum problem (dynamic programming).
	#2	Ulam Spiral Walkway	Straightforward.
	#3	Circular Primes	Straightforward.
	#4	The Ubiquitous 196	Straightforward.
	#5	Caesar’s Cipher	Trivial.
2007-01	#1	Filling The Cone	Trivial: Algebra. Plagiarized from DWITE 2006-01 #1.
	#2	Minesweeper	Straightforward. Plagiarized from DWITE 2005-01 #2.
	#3	Elapsed Time in Seconds	Date calculation.
	#4	Number Theory	Trivial if you know about the partition function.
	#5	Dutch Solitaire	Straightforward. Know how to use data structure libraries!

Links

• Official site
• Archived version

Last modified: 2008-04-29-Tue
Created: 2007-04-20-Fri

---