TweetFollow Us on Twitter

Dec 96 Challenge
Volume Number:12
Issue Number:12
Column Tag:Programmer’s Challenge

Programmer’s Challenge

by Bob Boonstra

Tangrams

The Challenge this month is to write code that will solve a tangram puzzle - that is, reassemble a two-dimensional shape that has been cut into a number of smaller shapes. The classic tangram consists of five right triangles of three different sizes, a square, and a rhomboid that are to be reassembled into a larger square. Your code will have to deal with a more general set of polygons. The prototype for the code you should write is:

#define kMaxVertices 10

typedef struct MyVertex {
 float  h;/* horizontal coordinate of vertex */
 float  v;/* vertical coordinate of vertex */
} MyVertex;

typedef struct MyPolygon {
    long     numVertices;/* number of vertices in polygon */
    MyVertex vertex[kMaxVertices];        /* vertex coordinates */
} MyPolygon;

typedef struct MyTransform {
    float     flipH;         /* optionally flip polygon about this horiz coordinate */
    float     rotateClockwise;      /* then rotate polygon clockwise by this many                                        
    radians */
    float     rotateCenterH;   /* around the point with this horiz coordinate */
    float     rotateCenterV;   /* and with this vertical coordinate */
    float     translateH;    /* then translate horizontally by this amount */
 float  translateV;/* then translate vertically by this amount */
    Boolean doFilp;                /* only perform flip if this is TRUE */
} MyTransform;

void SolveTangram(
    MyPolygon     *theShape,          /* shape to be reassembled */
    long     numHoles,            /* shape has this many holes (>=0) */
    MyPolygon     *theHoles[],  /* pointers to polygons that form the holes */
    long     numPieces,   /* number of pieces to reassemble */
    MyPolygon     *thePieces[],      /* shape and position of pieces to reassemble */
    MyTransform *theXForms[]      /* reassembly transforms corresponding to  thePieces */
);

The shape to be reassembled is a polygon pointed to by theShape, except that the reassembled shape may have some holes in it. The number of holes, which might be zero, is provided by numHoles, and the shape of the i-th hole is a polygon pointed to by theHoles[i]. You are to reassemble theShape using numPieces polygons pointed to by thePieces[]. For each piece, you should transform it to its correct position by optionally flipping it about a vertical axis, rotating it, and translating it, in that order. For the j-th piece, you should store the required transformation in the structure pointed to by theXForms[j]. Set doFilp to FALSE if no flip is needed, otherwise set doFilp to TRUE to flip the horizontal coordinates about the vertical axis with horizontal coordinate flipH. Set rotateClockwise to the number of radians that the piece should be rotated about the point (rotateCenterH, rotateCenterV). Finally, set translateH and translateV to the amount that the piece should be moved in the horizontal and vertical directions, respectively.

Calculations should be accurate to .00001, meaning that when I apply your transformations using the sin() and cos() library functions, the resulting positions should agree with theShape to within that accuracy.

All of the polygons will be legal polygons - no edge formed by a pair of adjacent vertices will intersect any other edge in the same polygon except at a vertex. The last vertex in each polygon connects to the first vertex (i.e., a square will have four vertices, not a fifth that is the same as the first). All of theHoles in the shape to be reassembled will be strictly inside theShape, not intersecting the edges. No hole will intersect any other hole. You may allocate up to 10MB of memory for your own use, provided you deallocate any allocated memory prior to returning.

This will be a native PowerPC Challenge, using the latest CodeWarrior environment. Solutions may be coded in C, C++, or Pascal. The winner will be the solution that solves my set of test tangrams in the shortest amount of time. And thanks go out to Ernst Munter for suggesting this Challenge - he wins two contest points for the suggestion.

Two Months Ago Winner

Congratulations to... Well, that is what you would normally read in this part of the column. Alas, the realities of publication deadlines have forced us to make a change in when we publish the winning solution. Perhaps an example of the publishing schedule for this, the December issue which ships in mid-November, would help me explain. Most of the articles for this issue were due to the editorial staff on September 23. Now, if that seems like a lot of lead time to you, it does to me also. However, people who know a lot more about publishing than I do assure me that This Is The Way It Is (e.g., most monthlies have 4-6 month lead times). I believe them - what does a software guy know about publishing deadlines anyway?

Well, I know enough simple arithmetic to realize that it is difficult to include a solution submitted on October 1 in an article due on September 23. The publishers, being just as good at arithmetic, also figured this out, so they have always given me a little extra time to write the Challenge column. That presented the magazine with a Challenge of its own, in that the Challenge column is very unpredictable in length, making magazine layout difficult.

We always try to guess how long the column is going to be, but that means guessing how long the winning solutions are going to be. Sometimes the solutions do not cooperate by being predictable in length. The Challenge deadlines (mine, not yours) kept creeping toward the 1st-of-the-month solution submission deadline. Sometimes there was only one day to compile the solutions, score them, select the winner, and write the column. Sometimes that one day was a day when that Real Job got in the way. (That’s right kids, you can’t make a living writing the Programmer’s Challenge column.) Soooo, in undeniable recognition of publishing reality and our continued goal of improving the magazine, we have reluctantly decided that we need to publish the winning solution three months after we publish the puzzle, instead of two. That is why you are reading this explanation instead of a description of the winning solution to the DNA Match Challenge.

Seriously though, this change will provide me with a more reasonable amount of time to analyze submitted solutions and hopefully point out more interesting and useful features of competitive solutions. For Challenge contestants, we will be announcing the identity of the winner on the CHALLENGE email list at approximately the time that we would have published under the previous arrangement. We hope that this change, in addition to restoring some sanity to the publishing schedule, will allow us to produce a more informative and interesting column. See you next month.


 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Vivaldi 1.9.818.44 - An advanced browser...
Vivaldi is a browser for our friends. In 1994, two programmers started working on a web browser. Our idea was to make a really fast browser, capable of running on limited hardware, keeping in mind... Read more
Skim 1.4.29 - PDF reader and note-taker...
Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file. Skim includes many features and has a... Read more
1Password 6.7.1 - Powerful password mana...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
FontExplorer X Pro 6.0.2 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
VOX 2.8.24 - Music player that supports...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
OmniPlan 3.7.1 - 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
Dropbox 24.4.17 - Cloud backup and synch...
Dropbox is an application that creates a special Finder folder that automatically syncs online and between your computers. It allows you to both backup files and keep them up-to-date between systems... Read more
WhatsApp 0.2.4238 - Desktop client for W...
WhatsApp is the desktop client for WhatsApp Messenger, a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for... Read more
SteerMouse 5.1 - Powerful third-party mo...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
OmniPlan Pro 3.7.1 - Professional-grade...
With OmniPlan Pro, 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

Latest Forum Discussions

See All

Fire Emblem Heroes event announces new m...
As reported yesterday, Nintendo was gearing up a live press event for their popular mobile game,Fire Emblem Heroes. While the stream revealed a lot of new things, the event was entirely in Japanese. Luckily we have a rundown of what was announced... | Read more »
Best games we played this week
Another week, another slate of new mobile games. Although there weren't as many big name releases as last week, there were plenty of unique video game titles that came out that's sure to keep you interested over the weekend. Everything from classic... | Read more »
Olli by Tinrocket (Photography)
Olli by Tinrocket 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Get drawn in with Olli by TinrocketOlli instantly turns your everyday moments into hand-drawn art and animations. • Watch... | Read more »
Penarium (Games)
Penarium 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: | Read more »
Fire Emblem Heroes is way more profitabl...
Profits for Nintendo's mobile game Fire Emblem Heroes are apparently impressive enough to beat out other Nintendo titles likeSuper Mario Run, despite having 10 times fewer downloads. [Read more] | Read more »
Classic series Robot Unicorn Attack 3 no...
The classic Adult Swim browser game, Robot Unicorn Attack, branched off into a series of popular mobile games. Now, the latest entry into the series, Robot Unicorn Attack 3, is available for iOS and Android mobile devices. [Read more] | Read more »
Sudoku Sweeper (Games)
Sudoku Sweeper 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: A minimalist mashup of Minesweeper and Sudoku. Logic puzzle perfection. Every row, column and zone contains a bomb and one of... | Read more »
Under Leaves (Games)
Under Leaves 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Journey into the forest, the jungle or the depths of the deep blue sea. Find chestnuts for the pigs, a caterpillar for the... | Read more »
Ninja Pizza Girl (Games)
Ninja Pizza Girl 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: In the not-so-distant future, rampart traffic congestion has resulted in only one way to deliver pizzas across town in thirty... | Read more »
SCRAP (Games)
SCRAP 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: That day, for no apparent reason, SCRAP decided to wake up and run. He had to, because his activation was a mistake the "Factory" could... | Read more »

Price Scanner via MacPrices.net

13-inch 2.9GHz/256GB Space Gray Touch Bar Mac...
B&H Photo has the 13″ 2.9GHz/256GB Space Gray Touch Bar MacBook Pro in stock today and on sale for $150 off MSRP including free shipping plus NY & NJ sales tax only: - 13″ 2.9GHz/256GB Touch... Read more
21-inch iMacs on sale for up to $151 off MSRP
B&H Photo has 21″ iMacs on sale for up to $151 off MSRP, each including free shipping plus NY sales tax only: - 21″ 3.1GHz iMac 4K: $1348 $151 off MSRP - 21″ 2.8GHz iMac: $1199.99 $100 off MSRP... Read more
Weekend deal: Up to $420 off new MacBook Pros...
Apple has Certified Refurbished 2016 15″ and 13″ MacBook Pros available for $230 to $420 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2.6GHz... Read more
Price drop: 15-inch 2.2GHz Retina MacBook Pro...
Amazon has dropped their price on 15″ 2.2GHz Retina MacBook Pros (MJLQ2LL/A) to $1709.99 including free shipping. Their price is $290 off MSRP for this model. Note that stock may sell out quickly at... Read more
2.8GHz Mac mini on sale for $899, save $100
B&H Photo has the 2.8GHz Mac mini (model number MGEQ2LL/A) on sale for $899 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. Read more
Check Apple prices on any device with the iTr...
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
New System Clock for macOS by B-Eng Now Avail...
Fehraltorf, Switzerland based B-Eng has announced the release and immediate availability of System Clock, the company’s new system monitor and information app developed exclusively for macOS. System... Read more
DEVONtechnologies Celebrates 15th Anniversary...
DEVONtechnologies celebrates its 15th company anniversary with a 30% discount on all its software products from May 1st through 5th, 2017. In spring 2002, DEVONtechnologies opened its website and... Read more
WaterField Designs Invites Customers to Help...
San Francisco based WaterField Designs invites customers and air travelers to participate in developing the next generation in-flight travel case, the Air Porter. Frustrated with limited legroom,... Read more
Save up to $260 with Apple refurbished 12-inc...
Apple has Certified Refurbished 2016 12″ Retina MacBooks available for $200-$260 off MSRP. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more

Jobs Board

*Apple* Mobile Master - Best Buy (United Sta...
**501505BR** **Job Title:** Apple Mobile Master **Location Number:** 000849-Gurnee-Store **Job Description:** **What does a Best Buy Apple Mobile Master do?** At Read more
Best Buy *Apple* Computing Master - Best Bu...
**498428BR** **Job Title:** Best Buy Apple Computing Master **Location Number:** 000293-Rockville-Store **Job Description:** **What does a Best Buy Apple Read more
*Apple* Mac Computer Technician - GeekHampto...
…complex computer issues over the phone and in person? GeekHampton, Long Island's Apple Premium Service Provider, is looking for you! Come work with our crew Read more
*Apple* Retail - Multiple Positions- Chicago...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Systems Engineer - California Polyte...
Cal Poly, San Luis Obispo Apple Systems Engineer Department: ITS - Customer & Tech Support (134900) College/Division: Academic Affairs Salary Range: Position Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.