# Search Results

• ### A new mission statement for my school's algorithms class

##### - by Eric Fode
The teacher at Eastern Washington University that is now teaching the algorithms course is new to eastern and as a result the course has changed drastically mostly in the right direction. That being said I feel that the class could use a more specific, and industry oriented (since that is where most students will go, though suggestions for an academia oriented class are also welcome) direction, having only worked in industry for 2 years I would like the community's (a wider and much more collectively experienced and in the end plausibly more credible) opinion on the quality of this as a statement for the purpose an algorithms class, and if I am completely off target your suggestion for the purpose of a required Jr. level Algorithms class that is standalone (so no other classes focusing specifically on algorithms are required). The statement is as follows: The purpose of the algorithms class is to do three things: Primarily, to teach how to learn, do basic analysis, and implement a given algorithm found outside of the class. Secondly, to teach the student how to model a problem in their mind so that they can find a an existing algorithm or have a direction to start the development of a new algorithm. Third, to overview a variety of algorithms that exist and to deeply understand and analyze one algorithm in each of the basic algorithmic design strategies: Divide and Conquer, Reduce and Conquer, Transform and Conquer, Greedy, Brute Force, Iterative Improvement and Dynamic Programming. The Question in short is: do you agree with this statement of the purpose of an algorithms course, so that it would be useful in the real world, if not what would you suggest?

• ### C# Algorithms for * Operator

##### - by Harsha
I was reading up on Algorithms and came across the Karatsuba multiplication algorithm and a little wiki-ing led to the Schonhage-Strassen and Furer algorithms for multiplication. I was wondering what algorithms are used on the * operator in C#? While multiplying a pair of integers or doubles, does it use a combination of algorithms with some kind of strategy based on the size of the numbers? How could I find out the implementation details for C#?

• ### I don't understand why algorithms are so special

##### - by Jessica
I'm a student of computer science trying to soak up as much information on the topic as I can during my free time. I keep returning to algorithms time and again in various formats (online course, book, web tutorial), but the concept fails to sustain my attention. I just don't understand: why are algorithms so special? I can tell you why fractals are awesome, why the golden ratio is awesome, why origami is awesome and scientific applications of all the above. Heck I even love Newton's laws and conical sections. But when it comes to algorithms, I'm just not astounded. They are not insightful in new ways about human cognition at all. I was expecting algorithms to be shattering preconceptions and mind-altering but time and time again they fail miserably. What am I doing wrong in my approach? Can someone tell me why algorithms are so awesome?

• ### What's a good, quick algorithms refresh?

##### - by Casey Patton
I have programming interviews coming up in a couple weeks. I took an algorithms class a while ago but likely forgot some key concepts. I'm looking for something like a very short book (< 100 pages) on algorithms to get back up to speed. Sorting algorithms, data structures, and any other essentials should be included. It doesn't have to be a book...just looking for a great way to get caught up in about a week. What's the best tool for a quick algorithms intro or refresher?

• ### What are the algorithms that are used for working with large data in popular web applications

##### - by Moss Farmer
I am looking for some well known algorithms that can be considered while handling very large amount of data.(Edit- By large amount of data I refer to records in a database excluding blobs). These algorithms if not in totality but in parts may be used in big web applications like Twitter, Last.fm , Amazon ,etc. Specifically, I'm looking for names or links to such algorithms. My primary interest lies in developing a very deep understanding on working with large database records and writing efficient code for working with the same.

• ### test cases for common algorithms [on hold]

##### - by Alexey
I need samples of test inputs and correct outputs for common algorithms for sorting, searching, data structures, graphs, etc. to check for mistakes in my future implementations. Can you advice resources with test cases? Or a website with community that implements algorithms and shares with results? Thanks! Edit: to clarify: I am going to implement forementioned algorithms for studying purposes and need inputs including large ones and correct outputs to better find mistakes in my implementations, since test cases that I can come up with on my own with might not be enough to reveal mistakes.

• ### Algorithms and Programmer's day-to-day job

##### - by Lior Kogan
As of July 10, 2012, Stack Overflow contains 3,345,864 questions, out of which 20,840 questions are tagged as "Algorithm" - this is less than 0.6% ! I find it disturbing. Many programmers have several years of academic education in computer science / software engineering. Most of them are smart... When asked, most would say that they love algorithms. Computer programming is generally about solving problems using algorithms... Yet, only 1 of 160 questions is tagged as algorithm related. What does it say about our profession?

• ### Easy to understand and interesting book on algorithms

##### - by gasan
Please advise me a book on algorithms, that would be easier to read and understand than Cormen's book1. It may be not so big and deep in explanation. I even want it to not be that big, however it shouldn't contain misconceptions or errors or inaccuracies. It should be a some kind of pre-Cormen's book, that will help later to understand more sophisticated conceptions. A beginner book (but still worth to read). 1 Introduction to Algorithms by Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and Clifford Stein

• ### problems with studying algorithms

##### - by rookie
hello everyone, I'm currently studying computer science at the Institute, and I have some problems with course which is named Algorithms, I've just begun to study it, but I'm already feeling, that I'm going to fail it, my problem is that while understanding different algorithms on graphs I need to keep in my mind a lot of info, and usually I can't do it, I forget some points of the exercise or can't proceed to final result, I'm very desperate about it cause I like programming very much. Did somebody feel the same while studying in the University? thanks in advance for any help P.S. I began to program only two years ago, may it be the problem?

• ### Sort algorithms that work on large amount of data

##### - by Giorgio
I am looking for sorting algorithms that can work on a large amount of data, i.e. that can work even when the whole data set cannot be held in main memory at once. The only candidate that I have found up to now is merge sort: you can implement the algorithm in such a way that it scans your data set at each merge without holding all the data in main memory at once. The variation of merge sort I have in mind is described in this article in section Use with tape drives. I think this is a good solution (with complexity O(n x log(n)) but I am curious to know if there are other (possibly faster) sorting algorithms that can work on large data sets that do not fit in main memory. EDIT Here are some more details, as required by the answers: The data needs to be sorted periodically, e.g. once in a month. I do not need to insert a few records and have the data sorted incrementally. My example text file is about 1 GB UTF-8 text, but I wanted to solve the problem in general, even if the file were, say, 20 GB. It is not in a database and, due to other constraints, it cannot be. The data is dumped by others as a text file, I have my own code to read this text file. The format of the data is a text file: new line characters are record separators. One possible improvement I had in mind was to split the file into files that are small enough to be sorted in memory, and finally merge all these files using the algorithm I have described above.

• ### Where to find algorithms work?

##### - by Misha
The funnest parts of my projects have been the back-end algorithms work. I have worked on projects where I implemented Gaussian Mixture models, a Remez algorithm and a few Monte Carlo schemes. I loved figuring out how these processes worked and tuning them when they didn't. I recently graduated and my problem lies in the work I was able to find. The only jobs I have found, with my Electrical Engineering degree, are for writing user applications. Tasks such as fashioning web interfaces or front-ends for hardware devices. When I speak with potential employers about my interests they say they have no work of the sort. Where does one find work that involves implementing these kind of schemes?

• ### What do I need to know about Data Structures and Algorithms in the "real" world

##### - by Ray T Champion
I just finished the data structures and algorithms course in school , I took it during the summer so 6wks course vs a 16 wk course during the regular semester. So not only was the course hard but it was really really really fast. My question is what do I need to know about data structures in the real world? I understand what they do and how they work, for the most part, but I had a real tough time coding them , I wouldn't be able to write the code for a binary tree class or a balanced tree class from scratch .... Is that bad? should I retake it , or is knowledge of how they work sufficient, without being able to write the classes from scratch?

• ### Color schemes generation - theory and algorithms

##### - by daniel.sedlacek
Hi I will be generating charts and diagrams and I am looking for some theory on color schemes and algorithm examples. Example questions: How to generate complementary or analogous colors? How to generate pastel, cold and warm colors? How to generate any number of random but distinct colors? How to translate all that to the hex triplet (web color)? My implementation will be in AS3 but any examples in metacode are welcome.

• ### Genetic algorithms with large chromosomes

##### - by Howie
I'm trying to solve the graph partitioning problem on large graphs (between a billion and trillion elements) using GA. The problem is that even one chromosome will take several gigs of memory. Are there any general compression techniques for chromosome encoding? Or should I look into distributed GA? NOTE: using some sort of evolutionary algorithm for this problem is a must! GA seems to be the best fit (although not for such large chromosomes). EDIT: I'm looking for state-of-the-art methods that other authors have used to solved the problem of large chromosomes. Note that I'm looking for either a more general solution or a solution particular to graph partitioning. Basically I'm looking for related works, as I, too, am attempting using GA for the problem of graph partitioning. So far I haven't found anyone that might have this problem of large chromosomes nor has tried to solve it.

• ### Functional programming and stateful algorithms

##### - by bigstones
I'm learning functional programming with Haskell. In the meantime I'm studying Automata theory and as the two seem to fit well together I'm writing a small library to play with automata. Here's the problem that made me ask the question. While studying a way to evaluate a state's reachability I got the idea that a simple recursive algorithm would be quite inefficient, because some paths might share some states and I might end up evaluating them more than once. For example, here, evaluating reachability of g from a, I'd have to exclude f both while checking the path through d and c: So my idea is that an algorithm working in parallel on many paths and updating a shared record of excluded states might be great, but that's too much for me. I've seen that in some simple recursion cases one can pass state as an argument, and that's what I have to do here, because I pass forward the list of states I've gone through to avoid loops. But is there a way to pass that list also backwards, like returning it in a tuple together with the boolean result of my canReach function? (although this feels a bit forced) Besides the validity of my example case, what other techniques are available to solve this kind of problems? I feel like these must be common enough that there have to be solutions like what happens with fold* or map. So far, reading learnyouahaskell.com I didn't find any, but consider I haven't touched monads yet. (if interested, I posted my code on codereview)

• ### Order of learning sort algorithms

##### - by user619818
I have already studied bubblesort, insertion sort and selection sort and can implement them in C pretty much from knowledge of the algorithm. I want to go on to learn shellsort, merge sort, heapsort and quicksort, which I guess are a lot harder to understand. What order should I take these other sort algos? I am assuming a simpler sort algo helps learn a more complex one. Don't mind taking on some others if it helps the learning process.

• ### Prefer algorithms to hand-written loops?

##### - by FredOverflow
Which of the following to you find more readable? The hand-written loop: for (std::vector<Foo>::const_iterator it = vec.begin(); it != vec.end(); ++it) { bar.process(*it); } Or the algorithm invocation: #include <algorithm> #include <functional> std::for_each(vec.begin(), vec.end(), std::bind1st(std::mem_fun_ref(&Bar::process), bar)); I wonder if std::for_each is really worth it, given such a simple example already requires so much code. What are your thoughts on this matter?

• ### How do I learn algorithms and data structures?

##### - by sushil bharwani
this is in continuation to my previous question where i asked is it necessary to learn algorithm and datastructures. I feel yes it is. Now when i work in a enviornment where i wont ever get the chance to learn it by experimenting or practically or in any assignment. What is the right approach like the right books, right kind of problems, right kind of resources that i can go through to give six months or a year or two to learn it. And also mould my mind in a way that it can relate problems to datastructures and algos.

• ### Algorithms for pairing a rating system to an assignment queue

##### - by blunders
Attempting to research how to allow a group of people to effectively rank a set of objects (each group member will have contributed one object to the group), and then assign each member an object that's not their own based on: Their ratings of the objects, Their objects rating, and The object remaining to be assigned. Idea is to attempt to assign objects to people based on the groups rating of their contribution to the group relative to other member's contribution, the the personal preferences expressed via the ratings. Any suggestions for: Further research, Refining the statement of the problem/solution, or A solution.

• ### Semantic algorithms

##### - by Mythago
I have a more theoretical than practical question. I'll start with an example - when I get an email and open it on my iPad, there is a feature, which recognizes the timestamp from the text and offers me to create an event in the calendar. Simply told, I want to know theoretically how it's done - I believe it's some kind of semantic parsing, and I would like if someone could point me to some resources, where I can read more about this.

• ### How to implement a genetic algorithm with distance, time, and cost

##### - by ari
I want to make a solution to find the optimum route of school visit. For example, I want to visit 5 schools (A, B, C, D, E) in my city. Then I must find out what school I should visit first, then the second, then the third etc. with distance, time, and cost criteria. The problem is, I am confused about how to use distance with time and cost (fuel usage) estimation in genetic algorithm to find the optimum route?

• ### Is the way I'm implementing my genetic algorithm right?

##### - by Mhjr
In my graduation project, I am asked to use a genetic algorithm (any variation of it can be chosen) to generate valid timetables. What I did was make a simple program that generates unique sequences representing genes, the sequence is described below: (sorry if it's mathematically incorrect) The only variable in the sequence is the room element, so basically the program takes a tree that goes like this: [Course] -(contains)-> [Units] -(contains)-> [Offerings] -(contains)-> [Instructors] -(contains)-> [Rooms] Each course can have n units (duplicates). Each unit can have n offerings (lectures,lab session, excercises,...). Each offering has only 1 instructor. Each instructor (or the whole lecture composed from the four elements of the sequence) has multiple rooms. When a timetable is initialized, one of these sequences that differ in rooms will be taken into the timetable, so the difference in genes (sequences) of each timetable will be just the rooms random choice and the difference between chromosomes (timetables) will be time placements of these genes (sequences). My question is, before I proceed in implementing what I described, is it valid? Is the representation used here for chromosomes a permutation representation?

• ### Which algorithms/data structures should I "recognize" and know by name?

##### - by Earlz
I'd like to consider myself a fairly experienced programmer. I've been programming for over 5 years now. My weak point though is terminology. I'm self-taught, so while I know how to program, I don't know some of the more formal aspects of computer science. So, what are practical algorithms/data structures that I could recognize and know by name? Note, I'm not asking for a book recommendation about implementing algorithms. I don't care about implementing them, I just want to be able to recognize when an algorithm/data structure would be a good solution to a problem. I'm asking more for a list of algorithms/data structures that I should "recognize". For instance, I know the solution to a problem like this: You manage a set of lockers labeled 0-999. People come to you to rent the locker and then come back to return the locker key. How would you build a piece of software to manage knowing which lockers are free and which are in used? The solution, would be a queue or stack. What I'm looking for are things like "in what situation should a B-Tree be used -- What search algorithm should be used here" etc. And maybe a quick introduction of how the more complex(but commonly used) data structures/algorithms work. I tried looking at Wikipedia's list of data structures and algorithms but I think that's a bit overkill. So I'm looking more for what are the essential things I should recognize?