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

Chromium 45.0.2454.85 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 45.0.2454.85: Note: Does not contain the "... Read more
OmniFocus 2.2.5 - GTD task manager with...
OmniFocus helps you manage your tasks the way that you want, freeing you to focus your attention on the things that matter to you most. Capturing tasks and ideas is always a keyboard shortcut away in... Read more
iFFmpeg 5.7.1 - Convert multimedia files...
iFFmpeg is a graphical front-end for FFmpeg, a command-line tool used to convert multimedia files between formats. The command line instructions can be very hard to master/understand, so iFFmpeg does... Read more
VOX 2.6 - Music player that supports man...
VOX is a beautiful music player that supports many filetypes. 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... Read more
Box Sync 4.0.6567 - Online synchronizati...
Box Sync gives you a hard-drive in the Cloud for online storage. Note: You must first sign up to use Box. What if the files you need are on your laptop -- but you're on the road with your iPhone? No... Read more
Carbon Copy Cloner 4.1.4 - Easy-to-use b...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
OmniGraffle Pro 6.3.1 - Create diagrams,...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
Monosnap 3.1.2 - Versatile screenshot ut...
Monosnap lets you capture screenshots, share files, and record video and .gifs! Capture: Capture full screen, just part of the screen, or a selected window Make your crop area pixel perfect with... Read more
Alfred 2.7.2 - Quick launcher for apps a...
Alfred is an award-winning productivity application for OS X. Alfred saves you time when you search for files online or on your Mac. Be more productive with hotkeys, keywords, and file actions at... Read more
Microsoft Remote Desktop 8.0.19 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more

We're Sorry to Report that Moonrise...
Moonrise is a very promising-looking, Pokemon-esque monster collecting and battling game that we were really looking forward to reviewing, but unfortunately it looks like that's never going to happen. [Read more] | Read more »
The Latest Update for The Sims FreePlay...
Commerce has gotten a little more active with the newest update for The Sims FreePlay, making Sunset Mall more of a hangout than ever before. [Read more] | Read more »
This Week at 148Apps: August 24-28, 2015
The Apps of August With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out... | Read more »
NASCAR in Real Racing 3? Sure, Why Not?
I have to give Firemonkeys credit - it's very cool of them to add NASCAR to Real Racing 3 via an update rather than making a separate game for it. But that's a different discussion for another time; for now let's sit back and enjoy driving in... | Read more »
The nuyu is an Inexpensive Activity Moni...
Today, Health o Meter nuyu has announced a series of health and fitness-related products, including the aforementioned activity monitor along with a wireless scale. All at a decent pricepoint, no less. [Read more] | Read more »
The Makers of Overkill are Trying Someth...
Craneballs, the studio responsible for the Overkill series, is taking a little break from all that violence (a little break) to bring us Cube Worm - a 3D take on one of the most classic PC/calculator games in existence. [Read more] | Read more »
The Sandbox Welcomes Cutethulu in its La...
Another month, another update to Pixowl's The Sandbox. This time players can say hello to "Cutethulu" - an adorable little rendition of perhaps the most well known (and infamous) of the Elder Gods. [Read more] | Read more »
ReBoard: Revolutionary Keyboard (Utilit...
ReBoard: Revolutionary Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $1.99, Version: 1.0 (iTunes) Description: Do everything within the keyboard without switching apps! If you are in WhatsApp, how do you schedule a... | Read more »
Tiny Empire (Games)
Tiny Empire 1.1.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1.3 (iTunes) Description: Launch cannonballs and blow tiny orcs into thousands of pieces in this intuitive fantasy-themed puzzle shooter! Embark on an... | Read more »
Astropad Mini (Productivity)
Astropad Mini 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: *** 50% off introductory price! ​*** Get the high-end experience of a Wacom tablet at a fraction of the price with Astropad... | Read more »

Price Scanner via MacPrices.net

eFileCabinet Announces SMB Document Managemen...
Electronic document management (EDM) eFileCabinet, Inc., a hosted solutions provider for small to medium businesses, has announced that its SecureDrawer and eFileCabinet Online services will be... Read more
WaterField Designs Unveils American-Made, All...
San Francisco’s WaterField Designs today unveiled their all-leather Cozmo 2.0 — an elegant attach laptop bag with carefully-designed features to suit any business environment. The Cozmo 2.0 is... Read more
Apple’s 2015 Back to School promotion: Free B...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
128GB MacBook Airs on sale for $100 off MSRP,...
B&H Photo has 11″ & 13″ MacBook Airs with 128GB SSDs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 11″ 1.6GHz/128GB MacBook Air: $799.99, $100 off MSRP... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
27-inch 3.2GHz iMac on sale for $1679, save $...
B&H Photo has the 27″ 3.2GHz iMac on sale for $1679.99 including free shipping plus NY sales tax only. Their price is $120 off MSRP. Read more
Apple and Cisco Partner to Deliver Fast-Lane...
Apple and Cisco have announced a partnership to create a “fast lane” for iOS business users by optimizing Cisco networks for iOS devices and apps. The alliance integrates iPhone with Cisco enterprise... Read more
Apple offering refurbished 2015 13-inch Retin...
The Apple Store is offering Apple Certified Refurbished 2015 13″ Retina MacBook Pros for up to $270 (15%) off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Apple refurbished 2015 MacBook Airs available...
The Apple Store has Apple Certified Refurbished 2015 11″ and 13″ MacBook Airs (the latest models), available for up to $180 off the cost of new models. An Apple one-year warranty is included with... Read more
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $999.99 $100 off - 21″ 2.7GHz iMac: $1199.99 $100 off - 21″ 2.9GHz iMac... Read more

Jobs Board

*Apple* Desktop Analyst - KDS Staffing (Unit...
…field and consistent professional recruiting achievement. Job Description: Title: Apple Desktop AnalystPosition Type: Full-time PermanentLocation: White Plains, NYHot Read more
Simply Mac- *Apple* Specialist- Store Manag...
Simply Mac is the largest premier retailer for Apple products and solutions. We're looking for dedicated individuals with a passion to simplify and enhance the Read more
*Apple* Evangelist - JAMF Software (United S...
The Apple Evangelist is responsible for building and cultivating strategic relationships with Apple 's small and mid-market business development field teams. This Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Desktop Analyst - KDS Staffing (Unit...
…field and consistent professional recruiting achievement. Job Description: Title: Apple Desktop AnalystPosition Type: Full-time PermanentLocation: White Plains, NYHot Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.