Here's the very dumb way: def divisorGenerator(n): for i in xrange(1,n/2+1): if n%i == 0: yield i yield n The result I'd like to get is similar to this one, but I'd like a smarter algorithm (this one it's too much slow and dumb :-) I can find prime factors and their multiplicity fast enough. I've an generator that ge...
This is for a small scheduling app. I need an algorithm to efficiently compare two "schedules", find differences, and update only the data rows which have been changed, as well as entries in another table having this table as a foreign key. This is a big question, so I'll say right away I'm looking for either general advice or specific...
I like to read about new and clever algorithms. And I like to think out of the box, so all kinds of algorithms from all fields of computation are welcome. From time to time I read research papers to keep up with the current research and expand my horizon. I also like to learn new tricks. Unfortunately I tend to concentrate only on my fi...
This is the one thing I could never get to work. My problem is to detect the end of one day and the start of the next and then splitting the diff into each day. Imagine you want to calculate a pay rate but it has to span across midnight. It also applies to calculating time to run on timed system, or time diff it should've run. ...
I am studying for cryptography and I somehow stuck on understanding how DES works. Because it is around for a long time there should be nice tutorials like fancy diagrams, videos etc around the net. I searched but with no luck. Has anyone spotted anything "easy-to-digest" for the brain? ...
What is an effective algorithm for nesting 1 dimensional lengths into predefined stock lengths? For example, If you required steel bars in the following quantities and lengths, 5 x 2 metres 5 x 3 metres 5 x 4 metres and these can be cut from 10 metre bars. How could you calculate the pattern for cutting the 10m bars so that the min...
I've written a little script to iterate across files in folders to count lines of code. The heart of the script is this function to count lines of whitespace, comments, and code. (Note that for the moment it is tailored to C# and doesn't know about multi-line comments). It just doesn't look very nice to me - has anyone got a cleaner ve...
There is an interesting post over here about this, in relation to cross-application flow of control. Well, recently, I've come across an interesting problem. Generating the nth value in a potentially (practically) endless recursive sequence. This particular algorithm WILL be in atleast 10-15 stack references deep at the point that it s...
I'm writing a little tile-based game, for which I'd like to support light sources. But my algorithm-fu is too weak, hence I come to you for help. The situation is like this: There is a tile-based map (held as a 2D array), containing a single light source and several items standing around. I want to calculate which tiles are lit up by th...
I have a website form that requires a US phone number input for follow up purposes, and this is very necessary in this case. I want try to eliminate users entering junk data 330-000-0000. I have seen some options of third parties that validate phone numbers for you, however idk if that is the best option for this situation. However if yo...
I'm trying to write a tennis reservation system and I got stucked with this problem. Let's say you have players with their prefs regarding court number, day and hour. Also every player is ranked so if there is day/hour slot and there are several players with preferences for this slot the one with top priority should be chosen. I'm thinki...
Now there's something I always wondered: how is sleep() implemented ? If it is all about using an API from the OS, then how is the API made ? Does it all boil down to using special machine-code on the CPU ? Does that CPU need a special co-processor or other gizmo without which you can't have sleep() ? The best known incarnation of sle...
I saw this question on Reddit, and there were no positive solutions presented, and I thought it would be a perfect question to ask here. This was in a thread about interview questions: Write a method that takes an int array of size m, and returns (True/False) if the array consists of the numbers n...n+m-1, all numbers in that range a...
Is there a way to generate a hash of a string so that the hash itself would be of specific length? I've got a function that generates 41-byte hashes (SHA-1), but I need it to be 33-bytes max (because of certain hardware limitations). If I truncate the 41-byte hash to 33, I'd probably (certainly!) lost the uniqueness. Or actually I suppo...
When developing a database of articles in a Knowledge Base (for example) - what are the best ways to sort and display the most relevant answers to a users' question? Would you use additional data such as keyword weighting based on whether previous users found the article of help, or do you find a simple keyword matching algorithm to be ...
Here's the jist of the problem: Given a list of sets, such as: [ (1,2,3), (5,2,6), (7,8,9), (6,12,13), (21,8,34), (19,20) ] Return a list of groups of the sets, such that sets that have a shared element are in the same group. [ [ (1,2,3), (5,2,6), (6,12,13) ], [ (7,8,9), (21,8,34) ], [ (19,20) ] ] Note the stickeyness - the set (6,...
I have a series of datetime objects and would like to calculate the average delta between them. For example, if the input was (2008-10-01 12:15:00, 2008-10-01 12:25:00, 2008-10-01 12:35:00), then the average delta would be exactly 00:10:00, or 10 minutes. Any suggestions on how to calculate this using Python? ...
Is there a master list of the Big-O notation for everything? Data structures, algorithms, operations performed on each, average-case, worst-case, etc. ...
given a matrix of distances between points is there an algorithm for determining a set of n-dimensional points that has these distances? (or at least minimises the error) sort of like a n-dimensional version of the turnpike problem. The best I can come up with is using multidimensional scaling. ...
I am interested to read and understand the 2D mesh algorithms. A search on Google reveals a lot of papers and sources, however most are too academic and not much on beginner's side. So, would anyone here recommend any reading sources ( suitable for the beginners), or open source implementation that I can learn from the start? Thanks. ...