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  • What types of programming contest problems are there?

    - by Alex
    Basically, I want to make a great reference for use with programming contests that would have all of the algorithms that I can put together that I would need during a contest as well as sample useage for the code. I'm planning on making this into a sort of book that I could print off and take with me to competitions. I would like to do this rather than simply bringing other books (such as Algorithms books) because I think that I will learn a lot more by going over all of the algorithms myself as well as I would know exactly what I have in the book, making it more efficient to have and use. So, I've been doing research to determine what types of programming problems and algorithms are common on contests, and the only thing I can really find is this (which I have seen referenced a few times): Hal Burch conducted an analysis over spring break of 1999 and made an amazing discovery: there are only 16 types of programming contest problems! Furthermore, the top several comprise almost 80% of the problems seen at the IOI. Here they are: Dynamic Programming Greedy Complete Search Flood Fill Shortest Path Recursive Search Techniques Minimum Spanning Tree Knapsack Computational Geometry Network Flow Eulerian Path Two-Dimensional Convex Hull BigNums Heuristic Search Approximate Search Ad Hoc Problems The most challenging problems are Combination Problems which involve a loop (combinations, subsets, etc.) around one of the above algorithms - or even a loop of one algorithm with another inside it. These seem extraordinarily tricky to get right, even though conceptually they are ``obvious''. Now that's good and all, but that study was conducted in 1999, which was 13 years ago! One thing I know is that there are no BigNums problems any more (as Java has a BigInteger class, they have stopped making those problems). So, I'm wondering if anyone knows of any more recent studies of the types of problems that may be seen in a programming contest? Or what the most helpful algorithms on contests would be?

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  • Pathfinding with MicroPather : costs calculations with sectors and portals

    - by Adan
    Hello, I'm considering using micropather to help me with pathfinding. I'm not using a discrete map : I'm working in 2d with sectors and portales. However, I'm just wondering what is the best way to compute costs with this library in this context. Just to be more clear about geometrical shapes I'm using : sectors are basically convex polygons, and portals are segments that lies on sector's edge. Micropather exposes a pure virtual Graph class that you must inherate and overrides 3 functions. I understand how pathfinding works, so there's no problem in overriding those functions. Right now, my implementation give me results, i.e I'm able to find a path in my map, but I'm not sure I'm using an optimal solution. For the AdjacentCost method : I just take the distance between sector's centers as the cost. I think a better solution should be to use the portal between the two sectors, compute its center, and then the cost should be : distance( sector A center, portal center ) + distance ( sector B center, portal center ). I'm pretty sure the approximation I'm using with just sector's center is enough for most cases, but maybe with thin and long sectors that are perpendicular, this approximation could mislead the A* algorithm. For the LeastCostEstimate method : I just take the midpoint of the two sectors. So, as you understand, I'm always working with sectors' centers, and it's working fine. And I'm pretty sure there's a better way to work. Any suggestions or feedbacks? Thanks in advance!

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  • Sort latitude and longitude coordinates into clockwise ordered quadrilateral

    - by Dave Jarvis
    Problem Users can provide up to four latitude and longitude coordinates, in any order. They do so with Google Maps. Using Google's Polygon API (v3), the coordinates they select should highlight the selected area between the four coordinates. Solutions and Searches http://www.geocodezip.com/map-markers_ConvexHull_Polygon.asp http://softsurfer.com/Archive/algorithm_0103/algorithm_0103.htm http://stackoverflow.com/questions/2374708/how-to-sort-points-in-a-google-maps-polygon-so-that-lines-do-not-cross http://stackoverflow.com/questions/242404/sort-four-points-in-clockwise-order http://en.literateprograms.org/Quickhull_%28Javascript%29 Graham's scan seems too complicated for four coordinates Sort the coordinates into two arrays (one by latitude, the other longitude) ... then? Jarvis March algorithm? Question How do you sort the coordinates in (counter-)clockwise order, using JavaScript? Code Here is what I have so far: // Ensures the markers are sorted: NW, NE, SE, SW function sortMarkers() { var ns = markers.slice( 0 ); var ew = markers.slice( 0 ); ew.sort( function( a, b ) { if( a.position.lat() < b.position.lat() ) { return -1; } else if( a.position.lat() > b.position.lat() ) { return 1; } return 0; }); ns.sort( function( a, b ) { if( a.position.lng() < b.position.lng() ) { return -1; } else if( a.position.lng() > b.position.lng() ) { return 1; } return 0; }); var nw; var ne; var se; var sw; if( ew.indexOf( ns[0] ) > 1 ) { nw = ns[0]; } else { ne = ns[0]; } if( ew.indexOf( ns[1] ) > 1 ) { nw = ns[1]; } else { ne = ns[1]; } if( ew.indexOf( ns[2] ) > 1 ) { sw = ns[2]; } else { se = ns[2]; } if( ew.indexOf( ns[3] ) > 1 ) { sw = ns[3]; } else { se = ns[3]; } markers[0] = nw; markers[1] = ne; markers[2] = se; markers[3] = sw; } What is a better approach? The recursive Convex Hull algorithm is overkill for four points in the data set. Thank you.

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  • C# .net How we valiadate a xml with Multiple xml-schemas

    - by allen8374
    <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope" xmlns:SOAP-ENC="http://www.w3.org/2003/05/soap-encoding" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:m0="http://www.MangoDSP.com/schema" xmlns:m1="http://www.onvif.org/ver10/schema"> <SOAP-ENV:Body> <m:CreateView xmlns:m="http://www.MangoDSP.com/mav/wsdl"> <m:View token=""> <m0:Name>View1</m0:Name> <m0:ProfileToken>AnalyticProfile1</m0:ProfileToken> <m0:IgnoreZone> <m0:Polygon> <m1:Point y="0.14159" x="0.12159"/> <m1:Point y="0.24159" x="0.34159"/> <m1:Point y="0.14359" x="0.94159"/> </m0:Polygon> </m0:IgnoreZone> <m0:SceneType>Outdoor</m0:SceneType> <m0:CustomParameters> <m0:CustomParameter> <m0:Name>ViewParam1</m0:Name> <m0:CustomParameterInt>0</m0:CustomParameterInt> </m0:CustomParameter> </m0:CustomParameters> <m0:SnapshotURI><!--This element is ignored for the create view request --> <m1:Uri>http://www.blabla.com</m1:Uri> <m1:InvalidAfterConnect>true</m1:InvalidAfterConnect> <m1:InvalidAfterReboot>true</m1:InvalidAfterReboot> <m1:Timeout>P1Y2M3DT10H30M</m1:Timeout> </m0:SnapshotURI> </m:View> </m:CreateView> </SOAP-ENV:Body> </SOAP-ENV:Envelope> xmlns:m="http://www.MangoDSP.com/mav/wsdl" as localfile:"ma.wsdl" xmlns:m0="http://www.MangoDSP.com/schema" as localfile:"MaTypes.xsd" how can i validate it.

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  • How do bezier handles work?

    - by user146780
    On Wikipedia I found information about bezier curves and made a function to generate the inbetween points for a bezier polygon. I noticed that Expression Design uses bezier handles. This allows a circle to be made with 4 points each with a bezier handle. I'm just not sure mathematically how this works in relation with the formula for bezier point at time T. How do these handle vectors work to modify the shape? Basically what's there relation to the bezier formula? Thanks

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  • Morphing from an image to a shape in Silverlight 3

    - by Moo
    Hi, I have a requirement to morph from an image (png) to a shape (polygon) in Silverlight 3 as an effect, but of course there is no built in transition or method to do this. At the moment the best I have is fade one out and the other in, but can anyone suggest a decent alternative that may work or look better? Regards Moo

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  • Plot points instead of lines? JFreeChart PolarChart

    - by billynomates
    Currently, the PolarChart joins all the coordinates with lines creating a polygon. I just want it to plot each point with a dot and NOT join them together. Is this possible? I have tried using translateValueThetaRadiusToJava2D() and Graphics2D to draw circles but it's very clunky and contrived. Any suggestions welcome!

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  • .NET Geometry Library

    - by dewald
    Does anyone know of a good (efficient, nice API, etc.) geometry open source library for .NET? Some of the operations needed: Data Structures Vectors (2D and 3D with floats and doubles) Lines (2D and 3D) Rectangles / Squares / Cubes / Boxes Spheres / Circles N-Sided Polygon Matrices (floats and doubles) Algorithms Intersection calculations Area / Volume calculations

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  • Criteria SpatialRestrictions.IsWithinDistance NHibernate.Spatial

    - by idjones82
    Has anyone implemented this, or know if it would be difficult to implement this/have any pointers? public static SpatialRelationCriterion IsWithinDistance(string propertyName, object anotherGeometry, double distance) { // TODO: Implement throw new NotImplementedException(); } from NHibernate.Spatial.Criterion.SpatialRestrictions I can use "where NHSP.Distance(PROPERTY, :point)" in hql. But want to combine this query with my existing Criteria query. for the moment I'm creating a rough polygon, and using criteria.Add(SpatialRestrictions.Intersects("PROPERTY", myPolygon));

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  • Inherited TShape.Paint does not work after overriding Shape property

    - by DarkWalker
    I'm to code a TExpandedShape class inherited from TShape. TExpandedShape must act like TShape and be able to draw extra shapes: Polygon and Star. Here is my code unit ExpandedShape; interface uses SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls, Forms, Dialogs, ExtCtrls, Windows; type TExpandedShapeType = ( stRectangle, stSquare, stRoundRect, stRoundSquare, stEllipse, stCircle, stPolygon, stStar ); TExpandedShape = class(TShape) private FShape: TExpandedShapeType; FEdgeCount: integer; procedure SetShape(const Value: TExpandedShapeType); procedure SetEdgeCount(const Value: integer); public procedure Paint; override; published property Shape : TExpandedShapeType read FShape write SetShape;// default stPolygon; property EdgeCount : integer read FEdgeCount write SetEdgeCount default 5; end; procedure Register; implementation procedure Register; begin RegisterComponents('Course', [TExpandedShape]); end; // TExpandedShape procedure TExpandedShape.Paint; begin case Shape of stStar : begin {Draw Star} end; stPolygon : begin {Draw Polygon} end; else begin {It is supposed to draw Circle, Rectangle etc, but it does not} inherited; end; end; end; procedure TExpandedShape.SetEdgeCount(const Value: integer); begin FEdgeCount := Value; Repaint; end; procedure TExpandedShape.SetShape(const Value: TExpandedShapeType); begin FShape := Value; Repaint; end; end. So, what is wrong? IMO TShape.Paint checks private value like FShape in case section and then decides what to draw. When inherited Paint method is called in my code it checks FShape value sees default 0 value [stRectangle] in there and draws it. PS: I did solve it with blackmagic way using Shape1 property instead of Shape one and if Shape1 value is not stPolygon or stStar i do like this: begin Shape := TShapeType(Shape1); inherited end; But this option is not really an option. I need a good short nice-looking one.

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  • Convet from line points to shape points

    - by VOX
    I have an array of points that make up a line. However I need to draw the line with the width of n pixels. How can I transform that points for lines to points for polygon (or a shape) so I can directly draw it on canvas. I'm developing two program at the same time, one is j2me and another is .NET CF. j2me doesn't support drawing lines with width. Please take a look at the picture. link text

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  • Mesh simplification

    - by Amrita
    I wish to develop a softare for 3D object compression (by polygon reduction) in flex using papervision 3D. Could you please suggest me an efficient algorithm for the same?

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  • Formatted input in c++

    - by julz666
    hey, i'm a noob to c++ (and coding in general) i'm looking for an easy way to take two doubles (at once) from the keyboard and store them in a struct i've created called "Point" and then ultimately store the Point into a vector of Points that's a member of a class (called "Polygon"). i know i could do it with a scanf but need to know how to do it with cin. hope that makes sense. thanks in advance julz

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  • Marshaling and Unmarshaling of kml codes for Google Earth

    - by Kayson
    May i inquire more knowledge on marshaling and unmarshaling of kml codes? Regarding those used in Google earth. I need to do a project on flight airlines, linking them with an arc which is a polygon to connect placemarks with placemarks. I've tried to compile sample codes of HelloKML but still unable to marshal and produce the kml codes itself. Please someone explain marshaling and unmarshaling of codes and producing of kml codes. Thanks in advance.

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  • MATLAB command for exporting geometry from pdetool

    - by lapwing
    I'm writing a MATLAB script which solves for the eigenmodes of a defined polygon. MATLAB's PDE toolbox lets me define the geometry using the command pdepoly() but I need to export the geometry description matrix manually to the workspace through the GUI before I can decompose, mesh, and solve the pde. Does anyone know either a command to export the geometry to the workspace or a better way to define this geometry description matrix in MATLAB? Many Thanks

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  • Make a compiled binary run at native speed flawlessly without recompiling from source on a another system?

    - by unknownthreat
    I know that many people, at a first glance of the question, may immediately yell out "Java", but no, I know Java's qualities. Allow me to elaborate my question first. Normally, when we want our program to run at a native speed on a system, whether it be Windows, Mac OS X, or Linux, we need to compile from source codes. If you want to run a program of another system in your system, you need to use a virtual machine or an emulator. While these tools allow you to use the program you need on the non-native OS, they sometimes have problems of performance and glitches. We also have a newer compiler called "JIT Compiler", where the compiler will parse the bytecode program to native machine language before execution. The performance may increase to a very good extent with JIT Compiler, but the performance is still not the same as running it on a native system. Another program on Linux, WINE, is also a good tool for running Windows program on Linux system. I have tried running Team Fortress 2 on it, and tried experiment with some settings. I got ~40 fps on Windows at its mid-high setting on 1280 x 1024. On Linux, I need to turn everything low at 1280 x 1024 to get ~40 fps. There are 2 notable things though: Polygon model settings do not seem to affect framerate whether I set it low or high. When there are post-processing effects or some special effects that require manipulation of drawn pixels of the current frame, the framerate will drop to 10-20 fps. From this point, I can see that normal polygon rendering is just fine, but when it comes to newer rendering methods that requires graphic card to the job, it slows down to a crawl. Anyway, this question is rather theoretical. Is there anything we can do at all? I see that WINE can run STEAM and Team Fortress 2. Although there are flaws, they can run at lower setting. Or perhaps, I should also ask, "is it possible to translate one whole program on a system to another system without recompiling from source and get native speed?" I see that we also have AOT Compiler, is it possible to use it for something like this? Or there are so many constraints (such as DirectX call or differences in software architecture) that make it impossible to have a flawless and not native to the system program that runs at native speed?

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  • Google maps Geometry Controls from GMaps Utility Library

    - by TiagoMartins
    hi everybody, i'm working on google maps in specifically on geometry controls the point is, in this example when I click in line or polygon infowindow show up, but the language is english (by default I think) can I change the language? in the tooltips i can replace the text, but in this particular case i have no place do replace it, this let me thinking that "language" is automatic, i'm wrong? best regards

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  • change attributes of SVG graph without refresh

    - by Mike Hudak
    Hello, I have a simple SVG graph generated by GraphViz: <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"> <!-- Generated by graphviz version 2.26.3 (20100126.1600) --> <!-- Title: G Pages: 1 --> <svg width="138pt" height="168pt" viewBox="0.00 0.00 138.00 168.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <g id="graph1" class="graph" transform="scale(1 1) rotate(0) translate(4 164)"> <title>G</title> <polygon fill="white" stroke="white" points="-4,5 -4,-164 135,-164 135,5 -4,5"/> <!-- Node1 --> <g id="node1" class="node"><title>Node1</title> <a xlink:href="http://localhost/viz/applet.php" xlink:title="Internet"> <image xlink:href="images/cloud.png" width="130px" height="77px" preserveAspectRatio="xMinYMin meet" x="0" y="-159.5"/> <text text-anchor="middle" x="65" y="-116.4" font-family="Times New Roman,serif" font-size="14.00">&#39;.$Internet.&#39;</text> </a> </g> <!-- Node2 --> <g id="node2" class="node"><title>Node2</title> <a xlink:href="http://localhost/viz/applet.php"> <image xlink:href="images/file server.png" width="44px" height="45px" preserveAspectRatio="xMinYMin meet" x="43" y="-45.5"/> </a> </g> <!-- Node1&#45;&gt;Node2 --> <g id="edge2" class="edge"><title>Node1&#45;&gt;Node2</title> <a xlink:title="Bandwidth: 1544kbps&#10;Using link: 12%&#10;VOIP calls: 4&#10;Packet rate: 10000&#10;Packet loss: 2"> <path fill="none" stroke="black" d="M65,-82.2678C65,-73.5404 65,-64.358 65,-55.8964"/> <polygon fill="black" stroke="black" points="68.5001,-55.6524 65,-45.6524 61.5001,-55.6525 68.5001,-55.6524"/> </a> </g> </g> </svg> I want to change some atributes: for example " VOIP calls: 4 " -changing "4" to value from Database(LDAP) without refreshing whole SVG graph <a xlink:title="Bandwidth: 1544kbps&#10;Using link: 12%&#10;VOIP calls: 4&#10;Packet rate: 10000&#10;Packet loss: 2"> Thank you for your answers

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  • Estimating the boundary of arbitrarily distributed data

    - by Dave
    I have two dimensional discrete spatial data. I would like to make an approximation of the spatial boundaries of this data so that I can produce a plot with another dataset on top of it. Ideally, this would be an ordered set of (x,y) points that matplotlib can plot with the plt.Polygon() patch. My initial attempt is very inelegant: I place a fine grid over the data, and where data is found in a cell, a square matplotlib patch is created of that cell. The resolution of the boundary thus depends on the sampling frequency of the grid. Here is an example, where the grey region are the cells containing data, black where no data exists. OK, problem solved - why am I still here? Well.... I'd like a more "elegant" solution, or at least one that is faster (ie. I don't want to get on with "real" work, I'd like to have some fun with this!). The best way I can think of is a ray-tracing approach - eg: from xmin to xmax, at y=ymin, check if data boundary crossed in intervals dx y=ymin+dy, do 1 do 1-2, but now sample in y An alternative is defining a centre, and sampling in r-theta space - ie radial spokes in dtheta increments. Both would produce a set of (x,y) points, but then how do I order/link neighbouring points them to create the boundary? A nearest neighbour approach is not appropriate as, for example (to borrow from Geography), an isthmus (think of Panama connecting N&S America) could then close off and isolate regions. This also might not deal very well with the holes seen in the data, which I would like to represent as a different plt.Polygon. The solution perhaps comes from solving an area maximisation problem. For a set of points defining the data limits, what is the maximum contiguous area contained within those points To form the enclosed area, what are the neighbouring points for the nth point? How will the holes be treated in this scheme - is this erring into topology now? Apologies, much of this is me thinking out loud. I'd be grateful for some hints, suggestions or solutions. I suspect this is an oft-studied problem with many solution techniques, but I'm looking for something simple to code and quick to run... I guess everyone is, really! Cheers, David

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  • Unresolved External Symbol linker error (C++)

    - by Niranjan
    Hi, I am trying to develop abstract design pattern code for one of my project as below.. But, I am not able to compile the code ..giving some compile errors(like "unresolved external symbol "public: virtual void __thiscall Xsecs::draw_lines(double,double)" (?draw_lines@Xsecs@@UAEXNN@Z)" ).. Can any one please help me out in this... #include "stdafx.h" #include <iostream> #include <vector> #include "Xsecs.h" using namespace std; //Product class class Xsecs { public: virtual void draw_lines(double pt1, double pt2); virtual void draw_curves(double pt1, double rad); }; class polyline: public Xsecs { public: virtual void draw_lines(double pt1,double pt2) { cout<<"draw_line in polygon"<<endl; } virtual void draw_curves(double pt1, double rad) { cout<<"Draw_curve in circle"<<endl; } /*void create_polygons() { cout<<"create_polygon_thru_draw_lines"<<endl; }*/ }; class circle: public Xsecs { public: virtual void draw_lines(double pt1,double pt2) { cout<<"draw_line in polygon"<<endl; } virtual void draw_curves(double pt1, double rad) { cout<<"Draw_curve in circle"<<endl; } /*void create_circles() { cout<<"Create circle"<<endl; }*/ }; //Factory class class Factory { public: virtual polyline* create_polyline()=0; virtual circle* create_circle()=0; }; class Factory1: public Factory { public: polyline* create_polyline() { return new polyline(); } circle* create_circle() { return new circle(); } }; class Factory2: public Factory { public: circle* create_circle() { return new circle(); } polyline* create_polyline() { return new polyline(); } }; int _tmain(int argc, _TCHAR* argv[]) { Factory1 f1; Factory * fp=&f1; return 0; }

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  • How to find the ocean using Google Maps API

    - by geejay
    I am trying to figure out where the ocean is in an arbitrary Google Maps view. I actually have the lat lon (a range of points, when joined together form the coastline) of the coastline. But how do I tell which side of this line is the coastline? One possible solution would be to find the latlon of the nearest service or town or business or something, and then the ocean is obviously on the other side (given a small enough enclosing polygon). Is there a better way?

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  • Creating SVG map from geometry stored in MySQL

    - by Barnabe
    I have a group of geometries stored in MySQl (as polygon and as well-known text) representing counties. I can build a table of geometries and color codes after querying some county data (say GDP per capita). What is the best way to export this as an SVG map? I cannot find any reference to SVG conversion in the MySQL documentation.

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