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  • Finding "spare time" in a day from within a list of events

    - by MFB
    I have a list of events which is always sorted chronologically. The start time is always followed by the end time. Times are strings formatted as 'HHmmss'. // list of events var events = [ '010000', // start '013000', // end... '053000', '060000', '161500', '184500'] // desired output var spares = [ '000000', // start '010000', // end... '013000', '053000', '060000', '161500', '184500', '235959'] How can I programmatically create a new list of "spare time" from 000000 to 235959? PS I'm trying to do this in Javascript, but any conceptual answer or pseudo code would be helpful too.

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  • algorithm for project euler problem no 18

    - by Valentino Ru
    Problem number 18 from Project Euler's site is as follows: By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23. 3 7 4 2 4 6 8 5 9 3 That is, 3 + 7 + 4 + 9 = 23. Find the maximum total from top to bottom of the triangle below: 75 95 64 17 47 82 18 35 87 10 20 04 82 47 65 19 01 23 75 03 34 88 02 77 73 07 63 67 99 65 04 28 06 16 70 92 41 41 26 56 83 40 80 70 33 41 48 72 33 47 32 37 16 94 29 53 71 44 65 25 43 91 52 97 51 14 70 11 33 28 77 73 17 78 39 68 17 57 91 71 52 38 17 14 91 43 58 50 27 29 48 63 66 04 68 89 53 67 30 73 16 69 87 40 31 04 62 98 27 23 09 70 98 73 93 38 53 60 04 23 NOTE: As there are only 16384 routes, it is possible to solve this problem by trying every route. However, Problem 67, is the same challenge with a triangle containing one-hundred rows; it cannot be solved by brute force, and requires a clever method! ;o) The formulation of this problems does not make clear if the "Traversor" is greedy, meaning that he always choosed the child with be higher value the maximum of every single walkthrough is asked The NOTE says, that it is possible to solve this problem by trying every route. This means to me, that is is also possible without! This leads to my actual question: Assumed that not the greedy one is the max, is there any algorithm that finds the max walkthrough value without trying every route and that doesn't act like the greedy algorithm? I implemented an algorithm in Java, putting the values first in a node structure, then applying the greedy algorithm. The result, however, is cosidered as wrong by Project Euler. sum = 0; void findWay(Node node){ sum += node.value; if(node.nodeLeft != null && node.nodeRight != null){ if(node.nodeLeft.value > node.nodeRight.value){ findWay(node.nodeLeft); }else{ findWay(node.nodeRight); } } }

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  • C# 5 Async, Part 3: Preparing Existing code For Await

    - by Reed
    While the Visual Studio Async CTP provides a fantastic model for asynchronous programming, it requires code to be implemented in terms of Task and Task<T>.  The CTP adds support for Task-based asynchrony to the .NET Framework methods, and promises to have these implemented directly in the framework in the future.  However, existing code outside the framework will need to be converted to using the Task class prior to being usable via the CTP. Wrapping existing asynchronous code into a Task or Task<T> is, thankfully, fairly straightforward.  There are two main approaches to this. Code written using the Asynchronous Programming Model (APM) is very easy to convert to using Task<T>.  The TaskFactory class provides the tools to directly convert APM code into a method returning a Task<T>.  This is done via the FromAsync method.  This method takes the BeginOperation and EndOperation methods, as well as any parameters and state objects as arguments, and returns a Task<T> directly. For example, we could easily convert the WebRequest BeginGetResponse and EndGetResponse methods into a method which returns a Task<WebResponse> via: Task<WebResponse> task = Task.Factory .FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Event-based Asynchronous Pattern (EAP) code can also be wrapped into a Task<T>, though this requires a bit more effort than the one line of code above.  This is handled via the TaskCompletionSource<T> class.  MSDN provides a detailed example of using this to wrap an EAP operation into a method returning Task<T>.  It demonstrates handling cancellation and exception handling as well as the basic operation of the asynchronous method itself. The basic form of this operation is typically: Task<YourResult> GetResultAsync() { var tcs = new TaskCompletionSource<YourResult>(); // Handle the event, and setup the task results... this.GetResultCompleted += (o,e) => { if (e.Error != null) tcs.TrySetException(e.Error); else if (e.Cancelled) tcs.TrySetCanceled(); else tcs.TrySetResult(e.Result); }; // Call the asynchronous method this.GetResult(); // Return the task from the TaskCompletionSource return tcs.Task; } We can easily use these methods to wrap our own code into a method that returns a Task<T>.  Existing libraries which cannot be edited can be extended via Extension methods.  The CTP uses this technique to add appropriate methods throughout the framework. The suggested naming for these methods is to define these methods as “Task<YourResult> YourClass.YourOperationAsync(…)”.  However, this naming often conflicts with the default naming of the EAP.  If this is the case, the CTP has standardized on using “Task<YourResult> YourClass.YourOperationTaskAsync(…)”. Once we’ve wrapped all of our existing code into operations that return Task<T>, we can begin investigating how the Async CTP can be used with our own code.

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  • ConcurrentDictionary<TKey,TValue> used with Lazy<T>

    - by Reed
    In a recent thread on the MSDN forum for the TPL, Stephen Toub suggested mixing ConcurrentDictionary<T,U> with Lazy<T>.  This provides a fantastic model for creating a thread safe dictionary of values where the construction of the value type is expensive.  This is an incredibly useful pattern for many operations, such as value caches. The ConcurrentDictionary<TKey, TValue> class was added in .NET 4, and provides a thread-safe, lock free collection of key value pairs.  While this is a fantastic replacement for Dictionary<TKey, TValue>, it has a potential flaw when used with values where construction of the value class is expensive. The typical way this is used is to call a method such as GetOrAdd to fetch or add a value to the dictionary.  It handles all of the thread safety for you, but as a result, if two threads call this simultaneously, two instances of TValue can easily be constructed. If TValue is very expensive to construct, or worse, has side effects if constructed too often, this is less than desirable.  While you can easily work around this with locking, Stephen Toub provided a very clever alternative – using Lazy<TValue> as the value in the dictionary instead. This looks like the following.  Instead of calling: MyValue value = dictionary.GetOrAdd( key, () => new MyValue(key)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would instead use a ConcurrentDictionary<TKey, Lazy<TValue>>, and write: MyValue value = dictionary.GetOrAdd( key, () => new Lazy<MyValue>( () => new MyValue(key))) .Value; This simple change dramatically changes how the operation works.  Now, if two threads call this simultaneously, instead of constructing two MyValue instances, we construct two Lazy<MyValue> instances. However, the Lazy<T> class is very cheap to construct.  Unlike “MyValue”, we can safely afford to construct this twice and “throw away” one of the instances. We then call Lazy<T>.Value at the end to fetch our “MyValue” instance.  At this point, GetOrAdd will always return the same instance of Lazy<MyValue>.  Since Lazy<T> doesn’t construct the MyValue instance until requested, the actual MyClass instance returned is only constructed once.

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  • finding houses within a radius

    - by paul smith
    During an interview I was asked given the following: A real estate application that lists all houses that are currently on the market (i.e., for sale) within a given distance (say for example the user wants to find all houses within 20 miles), how would you design your application (both data structure and alogirithm) to build this type of service? Any ideas? How would you implement it? I told him I didn't know becaue I've never done any geo-related stuff before.

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  • How does one unit test an algorithm

    - by Asa Baylus
    I was recently working on a JS slideshow which rotates images using a weighted average algorithm. Thankfully, timgilbert has written a weighted list script which implements the exact algorithm I needed. However in his documentation he's noted under todos: "unit tests!". I'd like to know is how one goes about unit testing an algorithm. In the case of a weighted average how would you create a proof that the averages are accurate when there is the element of randomness? Code samples of similar would be very helpful to my understanding.

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  • Algorithmic problem - quickly finding all #'s where value %x is some given value

    - by Steve B.
    Problem I'm trying to solve, apologies in advance for the length: Given a large number of stored records, each with a unique (String) field S. I'd like to be able to find through an indexed query all records where Hash(S) % N == K for any arbitrary N, K (e.g. given a million strings, find all strings where HashCode(s) % 17 = 5. Is there some way of memoizing this so that we can quickly answer any question of this form without doing the % on every value? The motivation for this is a system of N distributed nodes, where each record has to be assigned to at least one node. The nodes are numbered 0 - (K-1) , and each node has to load up all of the records that match it's number: If we have 3 nodes Node 0 loads all records where Hash % 3 ==0 Node 1 loads all records where Hash % 3 ==1 Node 2 loads all records where Hash % 3 ==2 adding a 4th node, obviously all the assignments have to be recomputed - Node 0 loads all records where Hash % 4 ==0 ... etc I'd like to easily find these records through an indexed query without having to compute the mod individually. The best I've been able to come up with so far: If we take the prime factors of N (p1 * p2 * ... ) if N % M == I then p % M == I % p for all of N's prime factors e.g. 10 nodes : N % 10 == 6 then N % 2 = 0 == 6 %2 N % 5 = 1 == 6 %5 so storing an array of the "%" of N for the first "reasonable" number of primes for my data set should be helpful. For example in the above example we store the hash and the primes HASH PRIMES (array of %2, %3, %5, %7, ... ]) 16 [0 1 1 2 .. ] so looking for N%10 == 6 is equivalent to looking for all values where array[1]==1 and array[2] == 1. However, this breaks at the first prime larger than the highest number I'm storing in the factor table. Is there a better way?

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  • What programming concept is used in Nokia Lumina City Lens application [closed]

    - by gowri
    I am totally impressed about the Nokia City Lens application. How does the Nokia Lumia City Lens app work? Nokia Lumia City Lens app detects shops, restaurants, etc. by scanning the visual environment. But how can it detect shops or anything by only scanning visual information? Because we need a 360 degree view to detect a location. Because we can't simply match visual information and get that data. The visuals will change proportionally with distance and angle. So how does this app match the location and retrieve the information? Can anyone explain the concept What technology or algorithm is used in this app?

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  • How to solve linear recurrences involving two functions?

    - by Aditya Bahuguna
    Actually I came across a question in Dynamic Programming where we need to find the number of ways to tile a 2 X N area with tiles of given dimensions.. Here is the problem statement Now after a bit of recurrence solving I came out with these. F(n) = F(n-1) + F(n-2) + 2G(n-1), and G(n) = G(n-1) + F(n-1) I know how to solve LR model where one function is there.For large N as is the case in the above problem we can do the matrix exponentiation and achieve O(k^3log(N)) time where k is the minimum number such that for all km F(n) does not depend on F(n-k). The method of solving linear recurrence with matrix exponentiation as it is given in that blog. Now for the LR involving two functions can anyone suggest an approach feasible enough for large N.

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  • "Bad apple" algorithm, or process crashes shared sandbox

    - by Roger Lipscombe
    I'm looking for an algorithm to handle the following problem, which I'm (for now) calling the "bad apple" algorithm. The problem I've got a N processes running in M sandboxes, where N M. It's impractical to give each process its own sandbox. At least one of those processes is badly-behaved, and is bringing down the entire sandbox, thus killing all of the other processes. If it was a single badly-behaved process, then I could use a simple bisection to put half of the processes in one sandbox, and half in another sandbox, until I found the miscreant. This could probably be extended by partitioning the set into more than two pieces until the badly-behaved process was found. For example, partitioning into 8 sets allows me to eliminate 7/8 of the search space at each step, and so on. The question If more than one process is badly-behaved -- including the possibility that they're all badly-behaved -- does this naive algorithm "work"? Is it guaranteed to work within some sensible bounds?

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  • When module calling gets ugly

    - by Pete
    Has this ever happened to you? You've got a suite of well designed, single-responsibility modules, covered by unit tests. In any higher-level function you code, you are (95% of the code) simply taking output from one module and passing it as input to the next. Then, you notice this higher-level function has turned into a 100+ line script with multiple responsibilities. Here is the problem. It is difficult (impossible) to test that script. At least, it seems so. Do you agree? In my current project, all of the bugs came from this script. Further detail: each script represents a unique solution, or algorithm, formed by using different modules in different ways. Question: how can you remedy this situation? Knee-jerk answer: break the script up into single-responsibility modules. Comment on knee-jerk answer: it already is! Best answer I can come up with so far: create higher-level connector objects which "wire" modules together in particular ways (take output from one module, feed it as input to another module). Thus if our script was: FooInput fooIn = new FooInput(1, 2); FooOutput fooOutput = fooModule(fooIn); Double runtimevalue = getsomething(fooOutput.whatever); BarInput barIn = new BarInput( runtimevalue, fooOutput.someOtherValue); BarOutput barOut = barModule(BarIn); It would become with a connector: FooBarConnectionAlgo fooBarConnector = new fooBarConnector(fooModule, barModule); FooInput fooIn = new FooInput(1, 2); BarOutput barOut = fooBarConnector(fooIn); So the advantage is, besides hiding some code and making things clearer, we can test FooBarConnectionAlgo. I'm sure this situation comes up a lot. What do you do?

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  • Is there a phrase or word to describe an algorithim or programme is complete in that given any value for its arguments there is a predictable outcome?

    - by Mrk Mnl
    Is there a phrase to describe an algorithim or programme is complete in that given any possible value for its arguments there is a predicatable outcome? i.e. all the ramifications have been considered whatever the context? A simple example would be the below function: function returns string get_item_type(int type_no) { if(type_no < 10) return "hockey stick" else if (type_no < 20) return "bulldozer" else return "unknown" } (excuse the dismal pseudo code) No matter what number is supplied all possibiblites are catered for. My question is: is there a word to fill the blank here: "get_item_type() is ______ complete" ? (The answer is not Turing Complete - that is something quite different - but I annoyingly always think of something as "Turing Complete" when I am thinking of the above).

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  • questions on a particular algorithm

    - by paul smith
    Upon searching for a fast primr algorithm, I stumbled upon this: public static boolean isP(long n) { if (n==2 || n==3) return true; if ((n&0x1)==0 || n%3==0 || n<2) return false; long root=(long)Math.sqrt(n)+1L; // we check just numbers of the form 6*k+1 and 6*k-1 for (long k=6;k<=root;k+=6) { if (n%(k-1)==0) return false; if (n%(k+1)==0) return false; } return true; } My questions are: Why is long being used everywhere instead of int? Because with a long type the argument could be much larger than Integer.MAX thus making the method more flexible? In the second 'if', is n&0x1 the same as n%2? If so why didn't the author just use n%2? To me it's more readable. The line that sets the 'root' variable, why add the 1L? What is the run-time complexity? Is it O(sqrt(n/6)) or O(sqrt(n)/6)? Or would we just say O(n)?

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  • Can a candidate be judged by asking to write a complex program on "paper"?

    - by iammilind
    Sometime back in an interview, I was asked to write following program: In a keypad of a mobile phone, there is a mapping between number and characters. e.g. 0 & 1 corresponds to nothing; 2 corresponds to 'a','b','c'; 3 corresponds to 'd','e','f'; ...; 9 corresponds to 'w','x','y','z'. User should input any number (e.g. 23, 389423, 927348923747293) and I should store all the combinations of these character mapping into some data structure. For example, if user enters "23" then possible character combinations are: ad, ae, af, bd, be, bf, cd, ce, cf or if user enters, "4676972" then it can be, gmpmwpa, gmpmwpb, ..., hnroxrc, ..., iosozrc Interviewer told that people have written code for this within 20-30 mins!! Also he insisted I have to write on paper. If I am writing a code then my tendency is as of I am writing production code, even though it may not be expected from me. So, I always try to think all the aspects like, optimization, readability, maintainability, extensible and so on. Considering all these, I felt that I should be writing on PC and it needs decent 2 hours. Finally after 25 mins, I was able to come up with just the concept and some shattered pieces of code (not to mention of my rejection). My question is not the answer for the above program. I want to know that is this a right way to judge the caliber of a person ? Am I wrong / too slow in the estimates ? Am I too idealistic ?

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  • Tournament bracket method to put distance between teammates

    - by Fred Thomsen
    I am using a proper binary tree to simulate a tournament bracket. It's preferred any competitors in the bracket that are teammates don't meet each other until the later rounds. What is an efficient method in which I can ensure that teammates in the bracket have as much distance as possible from each other? Are there any other data structures besides a tree that would be better for this purpose? EDIT: There can be more than 2 teams represented in a bracket.

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  • One dimensional cutting algorithm with minimum waste

    - by jm666
    Can anybody point me to some resources about "cutting algorithm"? The problem: have rods with length of L meters, e.g. 6 m need cut smaller pieces of different lengths, e.g. need: 4 x 1.2m 8 x 0,9m etc... (many other lengths and counts) How to determine the optimal cutting, what will produce the minimum wasted material? I'm capable write an perl program, but haven't any idea about the algorithm. (if here is already some CPAN module what can help, would be nice). Alternatively, if someone can point me to some "spreadsheet" solution, or to anything what helps. Ps: in addition, need care about the "cutting line width" too, whats means than from the 6m long rod is impossible to cut 6 x 1m, because the cutting itself takes "3mm" width, so it is possible cut only 5 x 1m and the last piece will be only 98.5 cm (1m minus 5 x 3mm cut-width) ;(.

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  • Conflict resolution for two-way sync

    - by K.Steff
    How do you manage two-way synchronization between a 'main' database server and many 'secondary' servers, in particular conflict resolution, assuming a connection is not always available? For example, I have an mobile app that uses CoreData as the 'database' on the iOS and I'd like to allow users to edit the contents without Internet connection. In the same time, this information is available on a website the devices will connect to. What do I do if/when the data on the two DB servers is in conflict? (I refer to CoreData as a DB server, though I am aware it is something slightly different.) Are there any general strategies for dealing with this sort of issue? These are the options I can think of: 1. Always use the client-side data as higher-priority 2. Same for server-side 3. Try to resolve conflicts by marking each field's edit timestamp and taking the latest edit Though I'm certain the 3rd option will open room for some devastating data corruption. I'm aware that the CAP theorem concerns this, but I only want eventual consistency, so it doesn't rule it out completely, right? Related question: Best practice patterns for two-way data synchronization. The second answer to this question says it probably can't be done.

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  • How to avoid or minimise use of check/conditional statement in my scenario?

    - by Muneeb Nasir
    I have scenario, where I got stream and I need to check for some value. If I got any new value I have to store it in any of data structure. It seems very easy, I can place conditional statement if-else or can use contain method of set/map to check either received is new or not. But the problem is checking will effect my application performance, in stream I will receive hundreds for value in second, if I start checking each and every value I received then for sure it effect performance. Anybody can suggest me any mechanism or algorithm to solve my issue, either by bypassing checks or at least minimize them?

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  • Need help on a problemset in a programming contest

    - by topher
    I've attended a local programming contest on my country. The name of the contest is "ACM-ICPC Indonesia National Contest 2013". The contest has ended on 2013-10-13 15:00:00 (GMT +7) and I am still curious about one of the problems. You can find the original version of the problem here. Brief Problem Explanation: There are a set of "jobs" (tasks) that should be performed on several "servers" (computers). Each job should be executed strictly from start time Si to end time Ei Each server can only perform one task at a time. (The complicated thing goes here) It takes some time for a server to switch from one job to another. If a server finishes job Jx, then to start job Jy it will need an intermission time Tx,y after job Jx completes. This is the time required by the server to clean up job Jx and load job Jy. In other word, job Jy can be run after job Jx if and only if Ex + Tx,y = Sy. The problem is to compute the minimum number of servers needed to do all jobs. Example: For example, let there be 3 jobs S(1) = 3 and E(1) = 6 S(2) = 10 and E(2) = 15 S(3) = 16 and E(3) = 20 T(1,2) = 2, T(1,3) = 5 T(2,1) = 0, T(2,3) = 3 T(3,1) = 0, T(3,2) = 0 In this example, we need 2 servers: Server 1: J(1), J(2) Server 2: J(3) Sample Input: Short explanation: The first 3 is the number of test cases, following by number of jobs (the second 3 means that there are 3 jobs for case 1), then followed by Ei and Si, then the T matrix (sized equal with number of jobs). 3 3 3 6 10 15 16 20 0 2 5 0 0 3 0 0 0 4 8 10 4 7 12 15 1 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 8 10 4 7 12 15 1 4 0 50 50 50 50 0 50 50 50 50 0 50 50 50 50 0 Sample Output: Case #1: 2 Case #2: 1 Case #3: 4 Personal Comments: The time required can be represented as a graph matrix, so I'm supposing this as a directed acyclic graph problem. Methods I tried so far is brute force and greedy, but got Wrong Answer. (Unfortunately I don't have my code anymore) Could probably solved by dynamic programming too, but I'm not sure. I really have no clear idea on how to solve this problem. So a simple hint or insight will be very helpful to me.

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  • algorithm for Virtual Machine(VM) Consolidation in Cloud

    - by devansh dalal
    PROBLEM: We have N physical machines(PMs) each with ram Ri, cpu Ci and a set of currently scheduled VMs each with ram requirement ri and ci respectively Moving(Migrating) any VM from one PM to other has a cost associated which depends on its ram ri. A PM with no VMs is shut down to save power. Our target is to minimize the weighted sum of (N,migration cost) by migrating some VMs i.e. minimize the number of working PMs as well as not to degrade the service level due to excessive migrations. My Approach: Brute Force approach is choosing the minimum loaded PM and try to fit its VMs to other PMs by First Fit Decreasing algorithm or we can select the victim PMs and target PMs based on their loading level and shut down victims if possible by moving their VMs to targets. I tried this Greedy approach on the Data of Baadal(IIT-D cloud) but It isn't giving promising results. I have also tried to study the Ant colony optimization for dynamic VM consolidating but was unable to understand very much. I used the links. http://dumas.ccsd.cnrs.fr/docs/00/72/52/15/PDF/Esnault.pdf http://hal.archives-ouvertes.fr/docs/00/72/38/56/PDF/RR-8032.pdf Would anyone please explain the solution or suggest any new approach for better performance soon. Thanks in advance.

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  • Create a fast algorithm for a "weighted" median

    - by Hameer Abbasi
    Suppose we have a set S with k elements of 2-dimensional vectors, (x, n). What would be the most efficient algorithm to calculate the median of the weighted set? By "weighted set", I mean that the number x has a weight n. Here is an example (inefficient due to sorting) algorithm, where Sx is the x-part, and Sn is the n-part. Assume that all co-ordinate pairs are already arranged in Sx, with the respective changes also being done in Sn, and the sum of n is sumN: sum <= 0; i<= 0 while(sum < sumN) sum <= sum + Sn(i) ++i if(sum > sumN/2) return Sx(i) else return (Sx(i)*Sn(i) + Sx(i+1)*Sn(i+1))/(Sn(i) + Sn(i+1)) EDIT: Would this hold in two or more dimensions, if we were to calculate the median first in one dimension, then in another, with n being the sum along that dimension in the second pass?

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  • Why did visual programming never take off and what future paradigms might change that?

    - by Rego
    As the number of "visual" OS's such as Android, iOS and the promised Windows 8 are becoming more popular, it does not seem to me that we programmers have new ways to code using these new technologies, due to a possible lack in new visual programming languages paradigms. I've seen several discussions about incompatibilities between the current coding development environment, and the new OS approaches from Windows 8, Android and other tablets OS's. I mean, today if we have a new tablet, it's almost a requirement for coding, to have, for instance, an external keyboard (due it seems to me it's very difficult to program using the touch screen), exactly because the coding assistance is not conceived to "write" thousands of lines of code. So, how advanced should be the "new" visual programming languages paradigms? Which characteristics these new paradigms would be required?

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  • Calculating WPM given a variable stream of input

    - by Jaxo
    I'm creating an application that sits in the background and records all key presses (currently this is done and working; an event is fired every keydown/keyup). I want to offer a feature for the user that will show them their WPM over the entire session the program has been running for. This would be easy if I added a "Start" and "End" button to activate a timer, but I need to detect only when the user is typing continuously - ignoring all one-time keyboard shortcuts and breaks the user takes from typing. How in the world do I approach this? Is this even realistically & accurately possible?

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  • Any algorithm to dedicate a set of known resources to a set of known requirements (scheduling)

    - by Saeed Neamati
    I'm developing an application to help school principals in dedicating teachers to classes and courses over the hours of a week (scheduling). The scenario is roughly something like this: User enters the list of teachers and their free times into the system User enters the list of courses for this semester User enters the list of available classes into the system Well, up to here, there is no big deal. Just simple CRUD operations and nothing extraordinary. However, now what makes this system useful is that the application should automatically and based on an algorithm create the semester scheduling. I think you've got the main idea here. For example application should suggest that teacher A should go to class 1 for mathematics, and at the same time teacher B should go to class 2 for physics. This way all of the classes would be dedicated to lessons and teacher times won't overlap each other. Piece a cake for school principal. However, I can't find a good algorithm for this resource dedication. I mean it seems hard to me. Searching Google resulted in articles from different websites, but they are of no help and use to me. For example: http://en.wikipedia.org/wiki/Resource_allocation or http://en.wikipedia.org/wiki/Scheduling_(production_processes) Is there any algorithm out there, or any application or engine which can help me here? Does this requirements have a known name, like for example time scheduling engine? Any help would be appreciated.

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  • Inexpensive generation of hierarchical unique IDs

    - by romaninsh
    My application is building a hierarchical structure like this: root = { 'id': 'root', 'children': [ { 'name': 'root_foo', 'children': [] }, { 'id': 'root_foo2', 'children': [ { 'id': 'root_foo2_bar', 'children': [] } ] } ] } in other words, it's a tree of nodes, where each node might have child elements and unique identifier I call "id". When a new child is added, I need to generate a unique identifier for it, however I have two problems: identifiers are getting too long adding many children takes slower, as I need to find first available id My requirement is: naming of a child X must be determined only from the state in their ancestors When I re-generate tree with same contents, the IDs must be same or in other words, when we have nodes A and B, creating child in A, must not affect the name given to children of B. I know that one way to optimize would be to introduce counter in each node and append it to the names which will solve my performance issue, but will not address the issue with the "long identifiers". Could you suggest me the algorithm for quickly coming up with new IDs?

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