breadth first or depth first search
I know how this algorithm works, but cant decide when to use which algorithm ? Are there some guidelines, where one better perform than other or any considerations ? Thanks very much. ...
algorithm
Parsing a semicolon-separated list
I have a semicolon-separated list of values, for example: strins s = "param1=true;param2=4;param3=2.0f;param4=sometext;"; I need a functions: public bool ExtractBool(string parameterName, string @params); public int ExtractInt(string parameterName, string @params); public float ExtractFloat(string parameterName, string @params); publ...
Fast dot product for a very special case
Given a vector X of size L, where every scalar element of X is from a binary set {0,1}, it is to find a dot product z=dot(X,Y) if vector Y of size L consists of the integer-valued elements. I suggest, there must exist a very fast way to do it. Let's say we have L=4; X[L]={1, 0, 0, 1}; Y[L]={-4, 2, 1, 0} and we have to find z=X[0]*Y[0] +...
What is the most efficient way to encode an arbitrary GUID into readable ASCII (33-127)?
Dear ladies and sirs. The standard string representation of GUID takes about 36 characters. Which is very nice, but also really wasteful. I am wondering, how to encode it in the shortest possible way using all the ASCII characters in the range 33-127. The naive implementation produces 22 characters, simply because 128 bits / 6 bits yiel...
Naive Bayesian classification (spam filtering) - Doubt in one calculation? Which one is right? Plz clarify
Hi guys, I am implementing Naive Bayesian classifier for spam filtering. I have doubt on some calculation. Please clarify me what to do. Here is my question. In this method, you have to calculate P(S|W) -> Probability that Message is spam given word W occurs in it. P(W|S) -> Probability that word W occurs in a spam message. P(W...
Grouping consecutive identical items: IEnumerable<T> to IEnumerable<IEnumerable<T>>
I've got an interresting problem: Given an IEnumerable<string>, is it possible to yield a sequence of IEnumerable<string> that groups identical adjacent strings in one pass? Let me explain. 1. Basic illustrative sample : Considering the following IEnumerable<string> (pseudo representation): {"a","b","b","b","c","c","d"} How to get...
Optimizing a Parking Lot Problem. What algorithims should I use to fit the most amount of cars in the lot?
What algorithms (brute force or not) would I use to put in as many cars (assume all cars are the same size) in a parking lot so that there is at least one exit (from the container) and a car cannot be blocked. Or can someone show me an example of this problem solved programmatically. The parking lot varies in shape would be nice but if ...
Combinatorial optimisation of a distance metric
I have a set of trajectories, made up of points along the trajectory, and with the coordinates associated with each point. I store these in a 3d array ( trajectory, point, param). I want to find the set of r trajectories that have the maximum accumulated distance between the possible pairwise combinations of these trajectories. My first ...
7 Card Poker Hand Evaluator
Hey, Does anyone know a fast algorithm for evaluating 7 card poker hands? Something which is more efficient than simply brute-force checking a every 21 5-card combination of hands from a set of 7. Cheers, Pete ...
LIFO stack algorithm design
I'm implementing a stack-based VM and I've been trying to read up on literature that explains or outlines algorithms for dealing with stacks no no avail. Here's an example: int i = 3 int j = 4 int k = 5 Lets assume i, j, and k are local variables so they would be traditionally stored on the stack. The assembly/bytecode translation wou...
Project Euler #163 understanding
I spent quite a long time searching for a solution to this problem. I drew tons of cross-hatched triangles, counted the triangles in simple cases, and searched for some sort of pattern. Unfortunately, I hit the wall. I'm pretty sure my programming/math skills did not meet the prereq for this problem. So I found a solution online in ord...
Adaptive user interface/environment algorithm
Hi all, I'm working on an information system (in C#) that (while my users use it) gathers statistical data on what pieces of information (tables & records) each user is requesting the most, and what parts of the interface he/she uses most. I'm using this statistical data to make the application adaptive to the user's needs, both in the...
Number of simple mutations to change one string to another?
Hi; I'm sure you've all heard of the "Word game", where you try to change one word to another by changing one letter at a time, and only going through valid English words. I'm trying to implement an A* Algorithm to solve it (just to flesh out my understanding of A*) and one of the things that is needed is a minimum-distance heuristic. ...
some examples for using specific searchalgorithm
I could understand the following search algorithms: Constraint Satisfaction with Arc Consistency, Uninformed search A* Search MinMax I would understand the definition and working principles of the above algorithm,but could you please give me some real world examples that the above algorithms will be suitable?My idea would be: For CSP...
Nested loop with dependent bounds trip count
hello. just out of curiosity I tried to do the following, which turned out to be not so obvious to me; Suppose I have nested loops with runtime bounds, for example: t = 0 // trip count for l in 0:N for k in 0:N for j in max(l,k):N for i in k:j+1 t += 1 t is loop trip count is there a general algorithm/...
Delete item from array in Java
What is wrong here? I want delete an item from an array, but it shows me error ArrayIndexOutBound exception public class delete { public static void main(String[]args) { int i; //delete item from array int k[] = new int[]{77,99,44,11,00,55,66,33,10}; //delete 55 int searchkey=55; ...
Find the centroid of a polygon with weighted vertices
Hi, I know how to find the centroid (center of mass) of a regular polygon. This assumes that every part of the polygon weighs the same. But how do I calculate the centroid of a weightless polygon (made from aerogel perhaps :), where each vertex has a weight? Simplified illustration of what I mean using straight line: 5kg-------------...
Count max rectangles number, that can be placed inside character
Hi, I need a solution for quite complex problem. Exactly, I need to calculate the number of rectangles that can be placed inside letter/character with given size, considering that all rectangles are the same size, but it(the size) and the letter/character(of some regular specific font) itself can be changed by user(this will be used as w...
Permutation algorithm in the form of..
R= repeats allowed -> 2 A= alphabet (1-10) S= space = 4; So we want example: [1][1][4][5] [1][7][4][5] [5][1][4][5] But need a fancy math formula to calculate this and all combinations ? ...
Logic to mirror byte value around 128
Hey, I have a need to mirror a byte's value around the centre of 128. So, example outputs of this function include: In 0 Out 255 In 255 Out 0 In 128 Out 128 In 127 Out 129 In 30 Out 225 In 225 Out 30 I'm driving myself nuts with this, I'm sure I'll kick myself when I read the answers. Cheers ...