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 determine most challenging test-cases to test any algorithm?

While solving any problem, we write algorithms. Some efficient, some not, some work, some fail. But sometimes we end up writing something which is mostly a success when we do a dry test run, perhaps, ...
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384 views

finds all possible permutations of a certain numbers of distinct digits

I am stuck on the following problem. I want to find an algorithm that finds all possible permutations of a certain numbers of distinct digits and then put them in a large matrix for instance. For ...
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How to find local maxima in matrices?

I need to develop an algorithm for finding all the local maxima in a two-dimensional array: how to search for local maxima in the the most efficient way? Are there algorithms about it? Moreover, the ...
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1answer
815 views

Linear probing hashing collision resolution

So I have a quick question about the linear probing method of collision resolution in hash tables. So by definition a linear probing method would look like: while (hashTable[hash] != null) hash = ...
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1answer
611 views

Functional Reactive/Relational Programming – Is there a difference?

I've been using Reactive Cocoa (by GitHub), a Functional Reactive Programming API for use with the Cocoa libraries for a while now, but have just read "Out of the Tar Pit", the paper that supposedly ...
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8answers
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What methods are there to avoid a stack overflow in a recursive algorithm?

Question What are the possible ways to solve a stack overflow caused by an recursive algorithm? Example I'm trying to solve Project Euler problem 14 and decided to try it with a recursive ...
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435 views

The physical implementation of quantum annealing algorithm

From that question about differences between Quantum annealing and simulated annealing, we found (in comments to answer) that physical implementation of quantum annealing exists (D-Wave quantum ...
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8answers
2k views

How meaningful is the Big-O time complexity of an algorithm?

Programmers often talk about the time complexity of an algorithm, e.g. O(log n) or O(n^2). Time complexity classifications are made as the input size goes to infinity, but ironically infinite input ...
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What is the difference between Quantum annealing and simulated annealing?

In both algorithms objective functions, that will be executed with non quantum computers, are used. Both algorithms are methods for finding the global minimum of a given objective function. From ...
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362 views

Transforming A Physical Algorithm into a Computerized One

I have realized that its possible to create algorithms that operate physically to solve problems much more efficiently than in a computer itself. Consider the following: Finding the shortest path ...
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2answers
818 views

Ring of numbers where adjacent entries sum up to a prime

Given a number n, find a permutation of the numbers 1...n such that all adjacent entries sum up to primes. If such a permutation does not exist, throw an error. Is there a purely-functional way to do ...
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1answer
133 views

Permuting a list of numbers by pushing and popping onto a stack

Suppose we have some long stack of numbers. There is another intermediate stack, and a destination stack to be returned in the end. The only two operations allowed is transferring the top of the old ...
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I'd like to write an “ultimate shuffle” algorithm to sort my mp3 collection

I'm looking for pseudocode suggestions for sorting my mp3 files in a way that avoids title and artist repetition. I listen to crooners - Frank Sinatra, Tony Bennett, Ella Fitzgerald etc. singing old ...
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heuristic for searching through non-perfectly sorted data

Given sorted data, the search solution is obvious. Given unsorted data, sensible options are sort then search or just linear search. This question is about what to do if the data is somewhat sorted, ...
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Is this a Proper “Rule” for Identifying the “Big O” Notation of an Algorithm?

I've been learning more about Big O Notation and how to calculate it based on how an algorithm is written. I came across an interesting set of "rules" for calculating an algorithms Big O notation and ...
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4answers
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Applications of heapsort [closed]

Heapsort is a sorting algorithm that has a time complexity of O(nlogn), and performs sorting using O(1) space complexity. However, I know that because it's unstable, it doesn't find many applications ...
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Possible Damerau-Levenshtein improvement?

I recently implemented the Damerau-Levenshtein distance algorithm from the pseudocode on Wikipedia. I couldn't find any explanation of exactly how it works and the pseudocode uses completely ...
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315 views

About Artificial Intelligence [closed]

I am interested in starting a career in artificial intelligence. Can anyone suggest how I could prepare for this? What languages should I study that would be best for this career choice?
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3answers
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What algorithm should I use to find the shortest path in this graph?

I have a graph with about a billion vertices, each of which is connected to about 100 other vertices at random. I want to find the length of the shortest path between two points. I don't care about ...
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1answer
154 views

Best way to clear balances between payers and payees

Say some 20 people go to a shop and everyone buys something. When it comes to paying, 5 of them pay the complete amount of 10,000$ split unequally between them. Since everyone bought different ...
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what is a efficient way to find repeating decimal

I am trying to find a efficient algorithm in Java to find the repeating decimal part of two integers a and b where a/b. eg. 5/7 = 0.714258 714258.... I currently only know of the long division ...
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1answer
209 views

Course Map Generator

My university lists the rotation of courses each semester/year. Therefore, it is possible to predict when every class will be taught. I am trying to create a JavaScript (language is irrelevant, ...
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1answer
1k views

Fast lookup hash map implementations

I'm in the process of implementing a programming language on top of LLVM. For my polymorphic system, I'm looking for suggestions for a ultra-fast dictionary. I am not concerned with insert time, as ...
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3answers
161 views

Search on multiple values

I have a database having around 15 tables.Currently I am working on a report generation page, which is having 16 criteria.The values are distributed among multiple tables.User can select any number of ...
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1answer
851 views

using ant colony algorithm to create cross word game [closed]

I have difficulty to learn about ant colony algorithm (ACO), I have read about generating crossword game using (genetic algorithm) GA.I Know both of GA ant ACO usually used for optimization, but my ...
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5answers
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Why interviewers want Optimal Algorithms

In an interview with a software company they asked me some algorithm design questions. Being strong in mathematics I was able to solve it mathematically, but each time when I propose my algorithm ...
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4answers
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How do you find the first common element in two arrays

How do you find the first common element in two arrays? My attempt: I looped through each at the same time and add the current value to a separate set for each of the lists. Also, check if the ...
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668 views

Programming interview: on sorted arrays, algorithm proof

The following is a programming interview question: Given 3 sorted arrays. Find(x,y,z), (where x is from 1st array, y is from 2nd array, and z is from 3rd array), such that Max(x,y,z) - Min(x,y,z) is ...
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Stereo images rectification and disparity: which algorithms?

I'm trying to figure out what are currently the two most efficent algorithms that permit, starting from a L/R pair of stereo images created using a traditional camera (so affected by some epipolar ...
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1answer
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A* Algorithm Completeness Proof

The A* Algorithm is the optimal (provided the heuristic function is underestimated), complete & admissible (provided some conditions). I know the proofs of admissibility & optimality. But how ...
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4answers
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Fastest way to find the closest point

I have a list in Python 2.7 of about 10000 point co-ordinates, like [(168, 245), (59, 52), (61, 250), ... (205, 69), (185, 75)] Is there a faster way to search for all the points in a bounding box, ...
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270 views

What sort of questions drive the decision as to whether similar code is separate or common?

I have come across the following problem many times in various guises in my programming career. As a simple example, consider the following: Let's say there is a method (B) that could differ ...
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3answers
649 views

Longest subsequence without string

Does there exist a dynamic programming algorithm to find the longest subsequence in a string X that does not contain Y as substring? Just that this problem seems so similar to other DP string ...
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1answer
193 views

LOOP program only need inc and zero

I have 4 different commands in LOOP programming language: y=Zero() y=Val(x)=copy x and put it in register y y=Inc(x)=x+1 y=Dec(x)=x-1 Finally I also have loop n times { ... ...
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1answer
180 views

LOOP-computable functions

I was just reading a chapter about LOOP-computable functions and I have the following question: Is it possible to numerate every LOOP program with an algorithm? Formally: Is it possible to have a ...
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Visiting points on a number line while minimizing a cost not related to distance

I need some help on this ACM ICPC problem. My current idea is to model this as a shortest path problem, which is described under the problem statement. Problem There are N = 1000 nuclear waste ...
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1answer
322 views

How to compute amoritized cost for a dynamic array?

I am trying to understand how to do the amortized cost for a dynamic table. Suppose we are using the accounting method. Let A of size m be an array of n elements. When n = m, then we create a new ...
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1answer
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Convert letters to numbers

I have the following problem. Given A=1, B=2 , ... , Z =26 I need an algorithm that given a letter combination, like the column order in excel, returns me the number/ AA=27 AB=28 ABC? Thanks a ...
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What could an algorithm look like that iterates through all combinations of two variables to aim at a certain number of entries?

For background information, see "Some background" further down. I have a list that looks like this: Start-Time-In-Seconds;End-Time-In-Seconds 1;2 4;6 12;15 ... This works together with a wave file ...
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1answer
385 views

What are the best algorithms out there to retrieve data from a file system?

This is my usecase: Traverse a filesystem, gauge its entire size and then upload it to Dropbox. Looks quite easy and is quite easy. Now if I do it using celery and spawn a thread for each ...
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1answer
514 views

OpenGL Image Load-Store Atomics Applications

I originally asked this on plain old stack but it was closed for being too open-ended. (Which was a good call as this is a better place for such questions.) Original Link: ...
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Try to find a word in the dictionary that has most letters given

I recently came across an algorithm design problem that I'd like some help with: Given some letters, for example a,e,o,g,z,k,l,j,w,n and a dictionary of words. Find a word in the dictionary that ...
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5answers
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Algorithm for matching similar content text items

I am working on a website (C#, ASP.Net MVC 3) which reads some RSS feeds from multiple sources and put feed title and summary in a database table(Sql Server). What I want to do is: Put an algorithm ...
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1answer
468 views

How can my code structure be improved? [closed]

I am looking for advice on the neatest way to structure my code. class Password { private string cipher; Password(string cipher) { this.cipher = cipher; } public string ...
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1answer
570 views

Algorithm to detect a CLICK within Square range

It might be a simple question but I am looking for optimal solution. I will have numbers printed on a screen and I will be aware of coordinates. Numbers/Symbols will have 4 points(Square) to define ...
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1answer
133 views

Algorithm for deciding change in gesture

I am developing an application where I am taking dynamic gestures as input and then mapping them to keyboard controls. By dynamic gesture, I mean for example hand moving from left to right or hand ...
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2answers
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Algorithm for dividing a range into ranges and then finding which range a number belongs to

Having a minimum a maximum number of ranges a value between minimum and maximum I'm trying to come up with a method, or two, which would calculate which range the provided value belongs to. For ...
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3answers
847 views

Algorithm for tracking progress of controller method running in background

I am using Codeigniter framework for PHP on Windows platform. My problem is I am trying to track progress of a controller method running in background. The controller extracts data from the ...
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1answer
142 views

overworld vs on-screen 2d tile organization

I am developing a 2d game where the world is made up of tiles. I have an overworld and a "current world": the current world represent the current tiles on screen at any given time, currently this ...
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1answer
290 views

Addition vs multiplication on algorithm performance

I am studying about optimizing alogrithms.(Prof. Skiena's Algorithm Guide book) One of the exercises asks us to optimize an algorithm: Suppose the following algorithm is used to evaluate the ...