TweetFollow Us on Twitter

Sep 92 Challenge
Volume Number:8
Issue Number:5
Column Tag:Programmers' Challenge

Programmers' Challenge

By Mike Scanlin, MacTutor Regular Contributing Author

Some things you cannot rush. The aging of a fine wine, the bearing of a child and copying files with Finder 7.0 are all things that take a prescribed amount of time. As much as you'd like to, you just can't accelerate certain processes. Putting together an issue of MacTutor is another such process. Article lead times being what they are, Programming Challenge questions will be separated from their winning solutions by two months. That is, the October issue will have the winning solution for the August Challenge, the November issue will have the winning solution for this September Challenge, and so on. So, for those of you waiting to find out the most efficient way to detect rubber banded pegs, you'll have to wait until next month. In the mean time, here's another Challenge for you to work on.

Programming Challenge of the Month - How many ways can you spell "cat"?

Given an order N (from 2 to 10) of a graph matrix and a character value for each node in the graph, calculate the number of unique paths that correctly spell out a given word (starting from any node). For instance, if N is 3 and the nodes are C, T, C, A, R, A, T, A and C, your input graph looks like figure 1.

Given an input word, say "CAT", you start at each of the 9 nodes and see how many unique paths there are that spell out "CAT". In this example, there are two solutions: (1,1), (2,1), (3,1) and (3,3), (3,2), (3,1). If the input word is "CAR", then there are four solutions: (1,1), (2,1), (2,2) and (1,3), (2,3), (2,2) and (3,3), (2,3), (2,2) and (3,3), (3,2), (2,2). For the input word "CATARACT" there are eight solutions.

Each path may cross any node any number of times but you cannot go diagonally from node to node, nor can you use the same node twice in a row (in the event of two letters next to each other in the input word that are the same). Don't worry about case sensitivity (assume everything is upper or lower case). The input word length is from 1 to 255 (a PString).

The goal is to find the number of unique paths (returned as a long). Here's the prototype:

long CountPaths(order, nodeValuesPtr, inputWordPtr)
short order;
char  *nodeValuesPtr;
StringPtr inputWordPtr;

Example:

Input:

order = 3

*nodeValuesPtr = "CTCARATAC"

*inputWordPtr = "\pCAT"

Output:

function result = 2

The winning solution will be the one that is (1) most correct, (2) fastest, (3) smallest (code size), and (4) elegant (in approximately that order of importance).

All solutions should be marked "Attn: Challenge Solution" and sent either via AppleLink or mail to Xplain Corporation (see page 2 for contact information).

And if you have any great ideas for future programming challenges send them in, too.

The Rules

Here’s how it works: Each month there will be a different programming challenge presented here. First, you must write some code that solves the challenge. Second, you must optimize your code (a lot). Then, submit your solution to MacTutor. A winner will be chosen based on code correctness, speed, size and elegance (in that order of importance) as well as the postmark of the answer. In the event of multiple equally desirable solutions, one winner will be chosen at random (with honorable mention, but no prize, given to the runners up). The prize for the best solution each month is $50 and a limited edition “I won the MacTutor Programming Challenge” T-shirt (not to be found in stores).1

In order to make fair comparisons between solutions, all solutions must be in ANSI compatible C. When timing routines, the latest version of THINK C will be used (with ANSI Settings plus “Honor ‘register’ first” and “Use Global Optimizer” turned on) so beware if you optimize for a different C compiler.

The solution and winners for a month’s Programmers’ Challenge will be published in the issue two months later (i.e., the solutions for August will appear in the October issue). The deadline for submitting a solution is a postmark of the 5th day of the month after the month printed on the front of this issue (i.e., the challenge in the August issue’s due date is October 5th).

All solutions should be marked “Attn: Programmers’ Challenge Solution” and sent to Xplain Corporation via snail mail or e-mail. If you send via snail mail, please include a disk with the solution and all related files (including contact information). See page 2 for information on “How to Contact Xplain Corporation.”

MacTutor reserves the right to publish any solution entered in the Programming Challenge of the Month and all entries are the property of MacTutor upon submission. The submission falls under all the same conventions of an article submission.

1 The prize is subject to change in the event of production problems.

 
AAPL
$97.23
Apple Inc.
-0.92
MSFT
$43.45
Microsoft Corpora
-0.13
GOOG
$583.21
Google Inc.
-4.21

MacTech Search:
Community Search:

Software Updates via MacUpdate

OmniPlan 2.3.6 - Robust project manageme...
With OmniPlan, you can create logical, manageable project plans with Gantt charts, schedules, summaries, milestones, and critical paths. Break down the tasks needed to make your project a success,... Read more
Command-C 1.1.1 - Clipboard sharing tool...
Command-C is a revolutionary app which makes easy to share your clipboard between iOS and OS X using your local WiFi network, even if the app is not currently opened. Copy anything (text, pictures,... Read more
Knock 1.1.7 - Unlock your Mac by knockin...
Knock is a faster, safer way to sign in. You keep your iPhone with you all the time. Now you can use it as a password. You never have to open the app -- just knock on your phone twice, even when it's... Read more
Mellel 3.3.6 - Powerful word processor w...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
LibreOffice 4.3.0.4 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
Freeway Pro 7.0 - Drag-and-drop Web desi...
Freeway Pro lets you build websites with speed and precision... without writing a line of code! With it's user-oriented drag-and-drop interface, Freeway Pro helps you piece together the website of... Read more
Drive Genius 3.2.4 - Powerful system uti...
Drive Genius is an OS X utility designed to provide unsurpassed storage management. Featuring an easy-to-use interface, Drive Genius is packed with powerful tools such as a drive optimizer, a... Read more
Vitamin-R 2.15 - Personal productivity t...
Vitamin-R creates the optimal conditions for your brain to work at its best by structuring your work into short bursts of distraction-free, highly focused activity alternating with opportunities for... Read more
Toast Titanium 12.0 - The ultimate media...
Toast Titanium goes way beyond the very basic burning in the Mac OS and iLife software, and sets the standard for burning CDs, DVDs, and now Blu-ray discs on the Mac. Create superior sounding audio... Read more
OS X Yosemite Wallpaper 1.0 - Desktop im...
OS X Yosemite Wallpaper is the gorgeous new background image for Apple's upcoming OS X 10.10 Yosemite. This wallpaper is available for all screen resolutions with a source file that measures 5,418... Read more

Latest Forum Discussions

See All

Plants vs. Zombies 2 Enters the Second H...
Plants vs. Zombies 2 Enters the Second Half of the Dark Ages Posted by Ellis Spice on July 31st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Why Does It Spin? (Games)
Why Does It Spin? 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: THERE'S ONLY ONE RULE: DON'T TOUCH THE WALLS! Do you think you're able to follow this simple rule even if you would have to... | Read more »
Ice Wings Plus (Games)
Ice Wings Plus 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: THE GREAT ENDLESS RUNNER OF COMBAT JETS IS BACK !! With more than 680.000 downloads in the App Store, Ice Wings: Skies of Steel... | Read more »
Murl the Squirrel (Games)
Murl the Squirrel 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Meet Murl. He is teased by a group of flying squirrels because he can't fly. Determined to show them he's can fly, he meets... | Read more »
Celleste (Games)
Celleste 0.1 Device: iOS Universal Category: Games Price: $2.99, Version: 0.1 (iTunes) Description: Lots of cute action with amazing 3D graphics and a new type of gameplay! Take control over the forces of the universe to help a group... | Read more »
Super Heavy Sword (Games)
Super Heavy Sword 0.0.1 Device: iOS Universal Category: Games Price: $.99, Version: 0.0.1 (iTunes) Description: Get Ready to Get HEAVY! Monster Robot Studios presents SUPER Heavy Sword! The sequel to the smash hit HEAVY sword which... | Read more »
Angels In The Sky (Games)
Angels In The Sky 1.00 Device: iOS Universal Category: Games Price: $6.99, Version: 1.00 (iTunes) Description: - A.I.S will only run smoothly on iPhone 5s. It's NOT compatible with iPad, iPhone 5 or earlier devices.- In order to... | Read more »
80 Days (Games)
80 Days 1.0.2 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.2 (iTunes) Description: 1872, with a steampunk twist. Phileas Fogg has wagered he can circumnavigate the world in just eighty days. Choose your own route... | Read more »
Micromon (Games)
Micromon 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: 130+ Animated Monsters to Catch & Battle! No waiting, play at your own pace! Embark on an epic monster capture RPG like none... | Read more »
Empire Manager (Games)
Empire Manager 1.0 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: Become ruler of an empire. Manage your economy, develop technology, hire an army and conquer the world in this addictive turn-... | Read more »

Price Scanner via MacPrices.net

iPad Cannibalization Threat “Overblown”
Seeking Alpha’s Kevin Greenhalgh observes that while many commentators think Apple’s forthcoming 5.5-inch panel iPhone 6 will cannibalize iPad sales, in his estimation, these concerns are being... Read more
Primate Labs Releases July 2014 MacBook Pro P...
Primate Labs’ John Poole has posted Geekbench 3 results for most of the new MacBook Pro models that Apple released on Tuesday. Poole observes that overall performance improvements for the new MacBook... Read more
Apple Re-Releases Bugfixed MacBook Air EFI Fi...
Apple has posted a bugfixed version EFI Firmware Update 2.9 a for MacBook Air (Mid 2011) models. The update addresses an issue where systems may take longer to wake from sleep than expected, and... Read more
Save $50 on the 2.5GHz Mac mini, plus free sh...
B&H Photo has the 2.5GHz Mac mini on sale for $549.99 including free shipping. That’s $50 off MSRP, and B&H will also include a free copy of Parallels Desktop software. NY sales tax only. Read more
Save up to $140 on an iPad Air with Apple ref...
Apple is offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. Stock tends to come and go with some of these... Read more
$250 price drop on leftover 15-inch Retina Ma...
B&H Photo has dropped prices on 2013 15″ Retina MacBook Pros by $250 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.3GHz Retina MacBook Pro: $2249, $250 off... Read more
More iPad Upgrade Musings – The ‘Book Mystiqu...
Much discussed recently, what with Apple reporting iPad sales shrinkage over two consecutive quarters, is that it had apparently been widely assumed that tablet users would follow a two-year hardware... Read more
13-inch 2.5GHz MacBook Pro on sale for $999,...
Best Buy has the 13″ 2.5GHz MacBook Pro available for $999.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $100 off MSRP. Price is... Read more
Save up to $300 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $300 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
WaterField Unveils 15″ Outback Solo & 13″...
Hard on the heels of Apple’s refreshed MacBook Pro Retina laptops announcement, WaterField Designs has unveiled a 15-inch version of the waxed-canvas and leather Outback Solo and a 13-inch version of... Read more

Jobs Board

Sr. Product Leader, *Apple* Store Apps - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
Sr Software Lead Engineer, *Apple* Online S...
Sr Software Lead Engineer, Apple Online Store Publishing Systems Keywords: Company: Apple Job Code: E3PCAK8MgYYkw Location (City or ZIP): Santa Clara Status: Full Read more
Sr Software Lead Engineer, *Apple* Online S...
Sr Software Lead Engineer, Apple Online Store Publishing Systems Keywords: Company: Apple Job Code: E3PCAK8MgYYkw Location (City or ZIP): Santa Clara Status: Full Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Sr. Product Leader, *Apple* Store Apps - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.