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  • What is the better approach to find if a given set is a perfect subset of a set - If given subset is

    - by Microkernel
    Hi guys, What is the best approach to find if a given set(unsorted) is a perfect subset of a main set. I got to do some validation in my program where I got to compare the clients request set with the registered internal capability set. I thought of doing by having internal capability set sorted(will not change once registered) and do Binary search for each element in the client's request set. Is it the best I could get? I suspected that there might be better approach. Any idea? Regards, Microkernel

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  • PHP Modify Array

    - by Ozzy
    Hi all, I have the following array: array(a, a, a, b, b, c, c, c, c, d, d); When I loop through it and echo it, the result is: a a a b b c c c c d d How ever I want to echo it in such a way that it displays: a b c d a b c d a c c Here is the array in a grid to better explain what im trying to achieve Current a a a b b c c c c d d What im tryin to do a b c d a b c d a c c How would I do this?

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  • Typecasting a floating value or using the math.h floor* functions?

    - by nobody
    Hi, I am coding up an implementation of Interpolation Search in C. The question is actually rather simple, I need to use the floating operations to do linear interpolation to find the correct index which will eventually be an integer result. In particular my probe index is: t = i + floor((((k-low)/(high-low)) * (j-i))); where, i,j,k,t are unsigned ints, and high,low are doubles. Would this be equivalent to: t = i + (unsigned int)(((k-low)/(high-low)) * (j-i)); Is there any reason I would actually want to use math.h floor* functions over just a simple (int) typecast?

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  • Is there a standard pattern for scanning a job table executing some actions?

    - by Howiecamp
    (I realize that my title is poor. If after reading the question you have an improvement in mind, please either edit it or tell me and I'll change it.) I have the relatively common scenario of a job table which has 1 row for some thing that needs to be done. For example, it could be a list of emails to be sent. The table looks something like this: ID Completed TimeCompleted anything else... ---- --------- ------------- ---------------- 1 No blabla 2 No blabla 3 Yes 01:04:22 ... I'm looking either for a standard practice/pattern (or code - C#/SQL Server preferred) for periodically "scanning" (I use the term "scanning" very loosely) this table, finding the not-completed items, doing the action and then marking them completed once done successfully. In addition to the basic process for accomplishing the above, I'm considering the following requirements: I'd like some means of "scaling linearly", e.g. running multiple "worker processes" simultaneously or threading or whatever. (Just a specific technical thought - I'm assuming that as a result of this requirement, I need some method of marking an item as "in progress" to avoid attempting the action multiple times.) Each item in the table should only be executed once. Some other thoughts: I'm not particularly concerned with the implementation being done in the database (e.g. in T-SQL or PL/SQL code) vs. some external program code (e.g. a standalone executable or some action triggered by a web page) which is executed against the database Whether the "doing the action" part is done synchronously or asynchronously is not something I'm considering as part of this question.

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  • Pointer-based binary heap implementation

    - by Derek Chiang
    Is it even possible to implement a binary heap using pointers rather than an array? I have searched around the internet (including SO) and no answer can be found. The main problem here is that, how do you keep track of the last pointer? When you insert X into the heap, you place X at the last pointer and then bubble it up. Now, where does the last pointer point to? And also, what happens when you want to remove the root? You exchange the root with the last element, and then bubble the new root down. Now, how do you know what's the new "last element" that you need when you remove root again?

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  • How to generate a number in arbitrary range using random()={0..1} preserving uniformness and density?

    - by psihodelia
    Generate a random number in range [x..y] where x and y are any arbitrary floating point numbers. Use function random(), which returns a random floating point number in range [0..1] from P uniformly distributed numbers (call it "density"). Uniform distribution must be preserved and P must be scaled as well. I think, there is no easy solution for such problem. To simplify it a bit, I ask you how to generate a number in interval [-0.5 .. 0.5], then in [0 .. 2], then in [-2 .. 0], preserving uniformness and density? Thus, for [0 .. 2] it must generate a random number from P*2 uniformly distributed numbers. The obvious simple solution random() * (x - y) + y will generate not all possible numbers because of the lower density for all abs(x-y)>1.0 cases. Many possible values will be missed. Remember, that random() returns only a number from P possible numbers. Then, if you multiply such number by Q, it will give you only one of P possible values, scaled by Q, but you have to scale density P by Q as well.

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  • Moving a unit precisely along a path in x,y coordinates

    - by Adam Eberbach
    I am playing around with a strategy game where squads move around a map. Each turn a certain amount of movement is allocated to a squad and if the squad has a destination the points are applied each turn until the destination is reached. Actual distance is used so if a squad moves one position in the x or y direction it uses one point, but moving diagonally takes ~1.4 points. The squad maintains actual position as float which is then rounded to allow drawing the position on the map. The path is described by touching the squad and dragging to the end position then lifting the pen or finger. (I'm doing this on an iPhone now but Android/Qt/Windows Mobile would work the same) As the pointer moves x, y points are recorded so that the squad gains a list of intermediate destinations on the way to the final destination. I'm finding that the destinations are not evenly spaced but can be further apart depending on the speed of the pointer movement. Following the path is important because obstacles or terrain matter in this game. I'm not trying to remake Flight Control but that's a similar mechanic. Here's what I've been doing, but it just seems too complicated (pseudocode): getDestination() { - self.nextDestination = remove_from_array(destinations) - self.gradient = delta y to destination / delta x to destination - self.angle = atan(self.gradient) - self.cosAngle = cos(self.angle) - self.sinAngle = sin(self.angle) } move() { - get movement allocation for this turn - if self.nextDestination not valid - - getNextDestination() - while(nextDestination valid) && (movement allocation remains) { - - find xStep and yStep using movement allocation and sinAngle/cosAngle calculated for current self.nextDestination - - if current position + xStep crosses the destination - - - find x movement remaining after self.nextDestination reached - - - calculate remaining direct path movement allocation (xStep remaining / cosAngle) - - - make self.position equal to self.nextDestination - - else - - - apply xStep and yStep to current position - } - round squad's float coordinates to integer screen coordinates - draw squad image on map } That's simplified of course, stuff like sign needs to be tweaked to ensure movement is in the right direction. If trig is the best way to do it then lookup tables can be used or maybe it doesn't matter on modern devices like it used to. Suggestions for a better way to do it? an update - iPhone has zero issues with trig and tracking tens of positions and tracks implemented as described above and it draws in floats anyway. The Bresenham method is more efficient, trig is more precise. If I was to use integer Bresenham I would want to multiply by ten or so to maintain a little more positional accuracy to benefit collisions/terrain detection.

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  • Managed code (C#) vs Matlabs and C++ for speed

    - by dotnetdev
    Hi, I am about to start developing an edge detection system (once I've read through a couple of books, which I'm doing so at good speed), but one thing I am wondering is the speed of an app like Matlabs (which can compile code to C++) vs AFORGE.NET for edge detecton. Is unmanaged code generally faster? Thanks

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  • Find the shortest path in a graph which visits certain nodes.

    - by dmd
    I have a undirected graph with about 100 nodes and about 200 edges. One node is labelled 'start', one is 'end', and there's about a dozen labelled 'mustpass'. I need to find the shortest path through this graph that starts at 'start', ends at 'end', and passes through all of the 'mustpass' nodes (in any order). ( http://3e.org/local/maize-graph.png / http://3e.org/local/maize-graph.dot.txt is the graph in question - it represents a corn maze in Lancaster, PA)

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  • sorting a doubly linked list with merge sort.

    - by user329820
    Hi I have found this code in the internet and it was for arrays ,I want to change it for doubly linked list(instead of index we should use pointer) would you please help me that how can i change merge method(I have changed sort method by myself) also this is not my home work ,I love working with linked list!! public class MergeSort { private DoublyLinkedList LocalDoublyLinkedList; public MergeSort(DoublyLinkedList list) { LocalDoublyLinkedList = list; } public void sort() { if (LocalDoublyLinkedList.size() <= 1) { return; } DoublyLinkedList listOne = new DoublyLinkedList(); DoublyLinkedList listTwo = new DoublyLinkedList(); for (int x = 0; x < (LocalDoublyLinkedList.size() / 2); x++) { listOne.add(x, LocalDoublyLinkedList.getValue(x)); } for (int x = (LocalDoublyLinkedList.size() / 2) + 1; x < LocalDoublyLinkedList.size`(); x++) {` listTwo.add(x, LocalDoublyLinkedList.getValue(x)); } //Split the DoublyLinkedList again MergeSort sort1 = new MergeSort(listOne); MergeSort sort2 = new MergeSort(listTwo); sort1.sort(); sort2.sort(); merge(listOne, listTwo); } private void merge(DoublyLinkedList a, DoublyLinkedList b) { int x = 0; int y = 0; int z = 0; while (x < first.length && y < second.length) { if (first[x] < second[y]) { a[z] = first[x]; x++; } else { a[z] = second[y]; y++; } z++; } //copy remaining elements to the tail of a[]; for (int i = x; i < first.length; i++) { a[z] = first[i]; z++; } for (int i = y; i < second.length; i++) { a[z] = second[i]; z++; } } }

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  • need suggestions about content filtering project

    - by serdar
    i'm thinking of designing and implementing a content filtering software as my graduation project. i want it to be a user contributed software. i mean, users can also add/categorize websites. it should be also a web project and extensions for browsers like chrome, firefox, ie.. my question is which programming language do you suggest for this project? i know that firefox extensions are javascript based maybe you can say use .net framework 3.5 because it's better in communication with extensions. sorry for my bad english.. btw any other suggessions about project will be good.. thx a lot.

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  • How to output multicolumn html without "widows"?

    - by user314850
    I need to output to HTML a list of categorized links in exactly three columns of text. They must be displayed similar to columns in a newspaper or magazine. So, for example, if there are 20 lines total the first and second columns would contain 7 lines and the last column would contain 6. The list must be dynamic; it will be regularly changed. The tricky part is that the links are categorized with a title and this title cannot be a "widow". If you have a page layout background you'll know that this means the titles cannot be displayed at the bottom of the column -- they must have at least one link underneath them, otherwise they should bump to the next column (I know, technically it should be two lines if I were actually doing page layout, but in this case one is acceptable). I'm having a difficult time figuring out how to get this done. Here's an example of what I mean: Shopping Link 3 Link1 Link 1 Link 4 Link2 Link 2 Link 3 Link 3 Cars Link 1 Music Games Link 2 Link 1 Link 1 Link 2 News As you can see, the "News" title is at the bottom of the middle column, and so is a "widow". This is unacceptable. I could bump it to the next column, but that would create an unnecessarily large amount of white space at the bottom of the second column. What needs to happen instead is that the entire list needs to be re-balanced. I'm wondering if anyone has any tips for how to accomplish this, or perhaps source code or a plug in. Python is preferable, but any language is fine. I'm just trying to get the general concept down.

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  • Revisions: algorithm and data structure

    - by SODA
    Hi, I need ideas for structuring and processing data with revisions. For example, I have a database of objects (e.g. cars). Each object has a number of properties, which can be arbitrary, so there's no a set schema to describe these objects. These objects are probably saved as key-value pairs. Now I need to change property of an object. I don't want to completely rewrite it - I want to be able to go back and see history of changes to these properties, that's why I want to add new property and keep the old one (so I guess a timestamp would do the job of telling which property is the latest). At the same time I want to be able to get info about any object in a snap, with only latest versions of each of the properties. Any ideas what would be the best approach? At least please point me in the right direction. Thanks!

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  • Aligning music notes using String matching algorithms or Dynamic Programming

    - by Dolphin
    Hi I need to compare 2 sets of musical pieces (i.e. a playing-taken in MIDI format-note details extracted and saved in a database table, against sheet music-taken into XML format). When evaluating playing against sheet music (i.e.note details-pitch, duration, rhythm), note alignment needs to be done - to identify missed/extra/incorrect/swapped notes that from the reference (sheet music) notes. I have like 1800-2500 notes in one piece approx (can even be more-with polyphonic, right now I'm doing for monophonic). So will I have to have all these into an array? Will it be memory overloading or stack overflow? There are string matching algorithms like KMP, Boyce-Moore. But note alignment can also be done through Dynamic Programming. How can I use Dynamic Programming to approach this? What are the available algorithms? Is it about approximate string matching? Which approach is much productive? String matching algos like Boyce-Moore, or dynamic programming? How can I assess which is more effective? Greatly appreciate any insight or suggestions Thanks in advance

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  • Most Frequent 3 page sequence in a weblog

    - by Sundararajan S
    Given a web log which consists of fields 'User ' 'Page url'. We have to find out the most frequent 3-page sequence that users takes. There is a time stamp. and it is not guaranteed that the single user access will be logged sequentially it could be like user1 Page1 user2 Pagex user1 Page2 User10 Pagex user1 Page 3 her User1s page sequence is page1- page2- page 3

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  • A graph problem

    - by copperhead
    I am struggling to solve the following problem http://uva.onlinejudge.org/external/1/193.html However Im not able to get a fast solution. And as seen by the times of others, there should be a solution of maximum n^2 complexity http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=3&page=show_problem&problemid=129&page=problem_stats Can I get some help?

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  • Algorithm for dragging objects on a fixed grid

    - by FlyingStreudel
    Hello, I am working on a program for the mapping and playing of the popular tabletop game D&D :D Right now I am working on getting the basic functionality like dragging UI elements around, snapping to the grid and checking for collisions. Right now every object when released from the mouse immediately snaps to the nearest grid point. This causes an issue when something like a player object snaps to a grid point that has a wall -or other- adjacent. So essentially when the player is dropped they wind up with some of the wall covering them. This is fine and working as intended, however the problem is that now my collision detection is tripped whenever you try to move this player because its sitting underneath a wall and because of this you cant drag the player anymore. Here is the relevant code: void UIObj_MouseMove(object sender, MouseEventArgs e) { blocked = false; if (dragging) { foreach (UIElement o in ((Floor)Parent).Children) { if (o.GetType() != GetType() && o.GetType().BaseType == typeof(UIObj) && Math.Sqrt(Math.Pow(((UIObj)o).cX - cX, 2) + Math.Pow(((UIObj)o).cY - cY, 2)) < Math.Max(r.Height + ((UIObj)o).r.Height, r.Width + ((UIObj)o).r.Width)) { double Y = e.GetPosition((Floor)Parent).Y; double X = e.GetPosition((Floor)Parent).X; Geometry newRect = new RectangleGeometry(new Rect(Margin.Left + (X - prevX), Margin.Top + (Y - prevY), Margin.Right + (X - prevX), Margin.Bottom + (Y - prevY))); GeometryHitTestParameters ghtp = new GeometryHitTestParameters(newRect); VisualTreeHelper.HitTest(o, null, new HitTestResultCallback(MyHitTestResultCallback), ghtp); } } if (!blocked) { Margin = new Thickness(Margin.Left + (e.GetPosition((Floor)Parent).X - prevX), Margin.Top + (e.GetPosition((Floor)Parent).Y - prevY), Margin.Right + (e.GetPosition((Floor)Parent).X - prevX), Margin.Bottom + (e.GetPosition((Floor)Parent).Y - prevY)); InvalidateVisual(); } prevX = e.GetPosition((Floor)Parent).X; prevY = e.GetPosition((Floor)Parent).Y; cX = Margin.Left + r.Width / 2; cY = Margin.Top + r.Height / 2; } } internal virtual void SnapToGrid() { double xPos = Margin.Left; double yPos = Margin.Top; double xMarg = xPos % ((Floor)Parent).cellDim; double yMarg = yPos % ((Floor)Parent).cellDim; if (xMarg < ((Floor)Parent).cellDim / 2) { if (yMarg < ((Floor)Parent).cellDim / 2) { Margin = new Thickness(xPos - xMarg, yPos - yMarg, xPos - xMarg + r.Width, yPos - yMarg + r.Height); } else { Margin = new Thickness(xPos - xMarg, yPos - yMarg + ((Floor)Parent).cellDim, xPos - xMarg + r.Width, yPos - yMarg + ((Floor)Parent).cellDim + r.Height); } } else { if (yMarg < ((Floor)Parent).cellDim / 2) { Margin = new Thickness(xPos - xMarg + ((Floor)Parent).cellDim, yPos - yMarg, xPos - xMarg + ((Floor)Parent).cellDim + r.Width, yPos - yMarg + r.Height); } else { Margin = new Thickness(xPos - xMarg + ((Floor)Parent).cellDim, yPos - yMarg + ((Floor)Parent).cellDim, xPos - xMarg + ((Floor)Parent).cellDim + r.Width, yPos - yMarg + ((Floor)Parent).cellDim + r.Height); } } } Essentially I am looking for a simple way to modify the existing code to allow the movement of a UI element that has another one sitting on top of it. Thanks!

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  • How to sort a list so that managers are always ahead of their subordinates (How do I do a topologica

    - by James Black
    I am working on a project using Groovy, and I would like to take an array of employees, so that no manager follows their subordinates in the array. The reason being that I need to add people to a database and I would prefer not to do it in two passes. So, I basically have: <employees> <employee> <employeeid>12</employeeid> <manager>3</manager> </employee> <employee> <employeeid>1</employeeid> <manager></manager> </employee> <employee> <employeeid>3</employeeid> <manager>1</manager> </employee> </employees> So, it should be sorted as such: employeeid = 1 employeeid = 3 employeeid = 12 The first person should have a null for managers. I am thinking about a binary tree representation, but I expect it will be very unbalanced, and I am not certain the best way to do this using Groovy properly. Is there a way to do this that isn't going to involve using nested loops?

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  • Converting to a column oriented array in Java

    - by halfwarp
    Although I have Java in the title, this could be for any OO language. I'd like to know a few new ideas to improve the performance of something I'm trying to do. I have a method that is constantly receiving an Object[] array. I need to split the Objects in this array through multiple arrays (List or something), so that I have an independent list for each column of all arrays the method receives. Example: List<List<Object>> column-oriented = new ArrayList<ArrayList<Object>>(); public void newObject(Object[] obj) { for(int i = 0; i < obj.length; i++) { column-oriented.get(i).add(obj[i]); } } Note: For simplicity I've omitted the initialization of objects and stuff. The code I've shown above is slow of course. I've already tried a few other things, but would like to hear some new ideas. How would you do this knowing it's very performance sensitive?

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  • Ideas for designing an automated content tagging system needed

    - by Benjamin Smith
    I am currently designing a website that amongst other is required to display and organise small amounts of text content (mainly quotes, article stubs, etc.). I currently have a database with 250,000+ items and need to come up with a method of tagging each item with relevant tags which will eventually allow for easy searching/browsing of the content for users. A very simplistic idea I have (and one that I believe is employed by some sites that I have been looking to for inspiration (http://www.brainyquote.com/quotes/topics.html)), is to simply search the database for certain words or phrases and use these words as tags for the content. This can easily be extended so that if for example a user wanted to show all items with a theme of love then I would just return a list of items with words and phrases relating to this theme. This would not be hard to implement but does not provide very good results. For example if I were to search for the month 'May' in the database with the aim of then classifying the items returned as realting to the topic of Spring then I would get back all occurrences of the word May, regardless of the semantic meaning. Another shortcoming of this method is that I believe it would be quite hard to automate the process to any large scale. What I really require is a library that can take an item, break it down and analyse the semantic meaning and also return a list of tags that would correctly classify the item. I know this is a lot to ask and I have a feeling I will end up reverting to the aforementioned method but I just thought I should ask if anyone knew of any pre-existing solution. I think that as the items in the database are short then it is probably quite a hard task to analyse any meaning from them however I may be mistaken. Another path to possibly go down would be to use something like amazon turk to outsource the task which may produce good results but would be expensive. Eventually I would like users to be able to (and want to!) tag content and to vote for the most relevant tags, possibly using a gameification mechanic as motivation however this is some way down the line. A temporary fix may be the best thing if this were the route I decided to go down as I could use the rough results I got as the starting point for a more in depth solution. If you've read this far, thanks for sticking with me, I know I'm spitballing but any input would be really helpful. Thanks.

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