In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning.

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How to code a one-sided virtual economy

I'm attempting to make an online game with a mini-economy in it. The challenge is that the only person selling anything will be the website itself, and hence the supply and demand curve doesn't apply ...
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66 views

Algorithm to find the fewest number of values (from a set of values) where the sum equals a value (+ one more condition)

The simplest way to explain this is with an example. You're given then number 19 and you have a set of numbers to choose from: 1, 2, 3, 4, 6 When choosing values from the list (which can be ...
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3answers
143 views

Concept for dealing with recurring appointments

Our company implemented a calendar system a few months back with recurring appointments, using iCal strings to store the recurring appointment criteria. We are starting to run into performance ...
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4k views

Is there any algorithm pattern to protect any content in the web to ensure I am the first one who created it?

A few years ago there was this hacker (don't remember who he was) that full disclosed a vulnerability in a given system, but to make sure nobody took credit for that, he created some kind of PGP key. ...
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53 views

Merge directed acyclic graphs minimizing number of nodes

I have some DAGs (directed acylic graphs) and I want to merge them in order to minimize the number of nodes (we could say that every node has a cost, while edges are free). These four different DAGs ...
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1answer
95 views

Permutting a list of numbers in order to get a list which satisfies given condition

Here is algorithmic problem I'm trying to solve: Given a list [x_1,x_2,...,x_n] return a permutation of elements of the list [y_1,y_2,...,y_n] (where for each i we have y_i = x_j for only one j) ...
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2answers
108 views

Porting an algorithm implementation licensed under GNU GPL v3

I'm working on a JavaScript port of a red-black tree implementation in Java from the book Algorithms 4th Edition, by Sedgewick and Wayne. I believe that my JavaScript port qualifies as a derivative ...
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1answer
161 views

Matching algorithms in context of data quality problems

I work for an organization that has lots of databases containing person information. The data quality is poor. One case was a surname I found like this (this is the worst-case scenario): Mark ...
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1answer
100 views

Matrices calculations on partial shape matching

I'm working in a shape recognition project where it is supposed for me to develop an application that receives two images: an original one and a sketch made by a user. I am supposed to detect contours ...
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2answers
94 views

Track a series of choices with a single number

I want to track a series of scored questions in a single number (the total score). Is that possible? and how? For example, I have 30 questions with either 3 or 2 choices. For any given question, the ...
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1answer
92 views

Finding same numbers in a matrix

I have a question here and I am trying to find a solution of it. But I want to see some other opinions as well. The problem is the following: There is a matrix NxN which holds integer numbers. ...
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1answer
115 views

Generate algorithm to solve peg solitaire

I know that with regression it is possible to generate a mathematical function based on experimental data. I was wondering, maybe there is a way to generate something more complex. I have a single ...
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1answer
84 views

How do I efficiently send notifications for different events to different users based on their preferences?

I'm creating a notification system for particular events. A user can set the criteria that match particular events (ie. New item, changed item, closed item etc) Items have different characteristics ...
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2answers
142 views

On-the-fly, random partition of a range of numbers [0,N] in groups of max M size

Suppose that you have a range of numbers from 0 to N that you want to randomly separate in groups of max M sequential numbers. This is easily done with a bitmap and a random number generator, but it ...
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3answers
123 views

Algorithm Analysis: In practice, do coefficients of higher order terms matter?

Consider an^2 + bn + c. I understand that for large n, bn and c become insignificant. I also understand that for large n, the differences between 2n^2 and n^2 are pretty insignificant compared to the ...
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82 views

Algorithm for sport tournament bracket tree

I would like to develop a library that: receive n players in input response with the tournaments brackets in output. I would ask you what kind of algorithm I have to use to choose the correct tree ...
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1answer
92 views

What algorithm-family or problem-space description fits? Industrial process feeding ingredients to process

Our process continuously feeds (normally <= 8) ingredients from a choice of hundreds, using 3 feeders only. So if ingredient count X is > 3, 3 through X are stirred together in a batch process and ...
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0answers
81 views

In a mutual credit network, how would you program an automatic jubilee?

A little explanation might be needed. I mean mutual credit the way that it's defined here: a type of alternative currency in which the currency used in a transaction can be created at the time of ...
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2answers
249 views

Most Efficient way to Compute the sum of divisors of N (1 ≤ N ≤ 1 000 000 000)

I want to write a code which computes the sum of divisors of a number N(1 ≤ N ≤ 1 000 000 000), excluding the number itself. However, I need an efficient way to do it. It suppose to print the answer ...
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1answer
154 views

moving around virtual keyboard

I'm creating virtual keyboard using javascript/html/css. And I can't find a good algorithm for moving from one button to another in different directions (top-bottom, left-right). Lets say I ...
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1answer
123 views

Is this still a Greedy Algorithm

As a preface I will state this is for a homework assignment. I have already discussed this with the professor and will not be using this design. This purpose of this question is whether or not the ...
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2answers
218 views

Why Do B+ Trees Have a Minimum Occupancy of 50%?

As far as I can tell, the basic operations (add, delete, search) on a B+ Tree would function the same if minimum occupancy was 1, or 1/3, or any other function on node size. All the sources available ...
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2answers
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Finding shortest path between nodes with a twist

Note: if you feel that I should include code, please tell me. I am solving a problem of finding shortest path between nodes. I am given the vertices between nodes, however they are one sided (ie you ...
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1answer
82 views

Find 'Connected Components' in undirected, unweighted graph coded as a 2d array

Given an undirected, unweighted graph coded as a 2d array, how can I find the number of different connected components? Example There is the following 2d array (I'm not putting any brackets to ...
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8answers
6k views

Function guaranteed to never return the same value twice [closed]

This is a question I was asked at a job interview, and I can't figure out the answer they were looking for, so I'm hoping someone here might have some ideas. The goal is to write a function that is ...
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1answer
59 views

Simulated Annealing Contradiction?

The entire idea of simulated annealing is to avoid getting stuck in local optimums, which is why sometimes, a worse solution is accepted. However, simulated annealing will automatically accept a ...
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1answer
318 views

Why does this evaluation function work in a connect four game in java

I am exploring how a Minimax algorithm can be used in a connect four game. I was looking through a program and found this evaluation function. private static int[][] evaluationTable = {{3, 4, 5, 7, ...
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1answer
69 views

Rideshare algorithm to be used for scheduled and adhoc journeys

I need some help writing some pseudo code for a rideshare system for taxi drivers. The idea behind it is that it would combine real-time incoming taxi journeys and pre-bookings in real-time. The ...
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1answer
133 views

What is the justification for the running time of this loop?

I don't understand why the running time of the following loop is n+2 ? Also why the running time of the statements inside the loop is n+1 ? Double test(int n){ int sum=0; -> 1 time ...
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4answers
297 views

Mark x% items in stream

There are n items (n is known and > 1,000,000,000). I want to randomly 'mark' x% of n-items in stream. (n and x are known) Items are in stream ,one directional (you can't go back) processed item ...
2
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1answer
89 views

Finding the fewest sets which contain all items

I am wondering if there is a known algorithm for solving the following. Data: There is a number of sets containing items. An item can be a member of more than one set. Aim: return the minimum number ...
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0answers
79 views

Walk Tree vs Zhang and Sasha Algorithms

I need some help understanding how two tree comparing algorithms differ. I am working with Microsoft's XmlDiffPatch (http://msdn.microsoft.com/en-us/library/aa302294.aspx) which compares two xmls. The ...
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1answer
136 views

Which algorithm best fits the following problem [closed]

I'm looking for the right algorithm to solve a specific problem. I hope that there are known algorithms that can be used. The problem definition Given a set of 'options' (~10) A session is defined ...
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2answers
181 views

Extracting first and last name from a single name field

I'm working with the Twitter API which provides only a single field called name, which includes the full name of a person. The application that we're constructing requires a first name and a last ...
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1answer
88 views

Handling the process of large-scale lists [closed]

What are the efficient ways to process huge lists (+10 millions), and things to consider while manipulating huge lists. First question, when should I use recursion, and when I shouldn't. In both ...
2
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2answers
196 views

An algorithm that spreads similar items across a list

I need an algorithm that distributes same items across a list, so maximizing the distance between occurrences. E.g. I have a list of 15 items: {a,b,c,c,c,d,e,f,f,f,g,h,h,i,j} The algorithm should ...
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2answers
944 views

How to calculate figure rotation efficiently?

I have a Figure represented through a matrix of bytes (bitmap-like matrix). Example Figure is shown on the Picture 1. The goal is to find the best rotation angle of some given Figure. When Figure ...
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1answer
249 views

How to find duplicate strings

I allow my user to create profiles, meaning they potentially could create some with duplicate names. This can be problematic so I want to prevent them from doing so. I coded up this first pass ...
3
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1answer
196 views

What advantages are there to using Flex/Bison over just writing a compiler straight in a programming language?

I have written an Interpreter / Compiler simply as a programming algorithm using features such as recursive functions and concepts from finite-State machines. To me, these things are ideally suited to ...
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1answer
244 views

Assembly vs. algorithmic languages (like C, Algol, etc)

Usually, computer science papers describe algorithms in Algol-like pseudolanguage, similar to Pascal or even C/C++. But Donald Knuth uses his own assembly language (MMIX). Are there any good known ...
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2answers
206 views

Finding common prefixes for a set of strings

I am trying to find common prefixes for a sorted set of strings. i.e. if the following strings are given: AB123456 AB123457 ABCDEFGH ABCDEFGX1 ABCDEFGY XXXX then my function should return three ...
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65 views

Does multiple Bloom filters make sense?

In order to decrease the number of false positives, I came up with a couple of possible solutions. Create two different types of Bloom filters; eg. filter1 using 3 different hash algorithms, filter2 ...
2
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1answer
224 views

Quickest sorting algorithm for sorting a low number of integers

I am making a program on my spare time that I want to run as quickly as possible. The program is written in C. A large set of the procedures operate on pointers to 7 integers that are sorted by their ...
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1answer
120 views

how to write example code for this sequence number? [closed]

I want to ask you a question. How is the example code (just an algorithm in any language programming) for this sequence: 1, 2, 3, 1, 4, 2, 5, 3, 4, 5, 1, 6, 2, 7, 3, 6, 4, 7, 5, 6, 7, 1, 8, ... It ...
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1answer
102 views

Method ordering

This is the type of question that one would probably get in an exam, but now it happens to be in the real word. :-) I would appreciate some advice regarding the datastructure/algorithm that can be ...
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2answers
68 views

multiple comparison sorting

I have a set of songs where I want to sort them by a particular quality. In order to do this (by crowdsourcing) I will present users with a comparison between two songs. The user will then choose ...
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4answers
307 views

Order by different Enum property each row

So I have a list of DefaultSearchModal items that have an enum called TypeSearch in every list item. I would like to order the list to have a different enum property each row. So if you have an ...
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1answer
81 views

How to compute data for charting?

I'm building a charting component that displays data directly from the raw data records. It should be able to filter data (subset) and then perform some rudimentry maths on the data (sum, avg, etc). ...
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Incorporating custom Algorithm in SOLR-LUCENE , before Indexing?

CURRENT FLOW: I am using a custom algorithm(presently in php) to rank the MYSQL records before INDEXING it to SOLR . WHAT I WANT : Is it possible implementing this ALGORITHM(may be in JAVA) inside ...
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1answer
97 views

Min weight feedback edge set with DFS?

Exercise from The Algorithm Design Manual 6-10. [4] Let G = (V,E) be an undirected graph. A set F ⊆ E of edges is called a feedback-edge set if every cycle of G has at least one edge in F. ...