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.

learn more… | top users | synonyms (1)

3
votes
1answer
415 views

Suitable algorithm for joining records from multiple databases

I am in the process of writing a library that is used to be able to access data from a database. The library requires the initial definition of all the tables that the application will be using in the ...
5
votes
4answers
903 views

Find the peak of each islands in sparse matrix

I have a sparse matrix that contains several islands of unknown size. I would like to find the highest peak of each islands. Consider this matrix as an example: 0 0 1 0 0 0 0 0 0 1 2 1 0 0 0 0 0 3 2 ...
2
votes
3answers
6k views

What is the time complexity of the algorithm to check if a number is prime?

What is the time complexity of the algorithm to check if a number is prime? This is the algorithm : bool isPrime (int number) { if (number < 2) return false; if (number == 2) return ...
0
votes
1answer
687 views

Priority queue for Kruskal's algorithm with running time O(E lg V)

I'm reviewing my notes on Kruskal's algorithm and have a question about getting the runtime down to O(E lg V). By using a PQ with edges and a boolean array of which vertices we have added to our tree ...
1
vote
1answer
663 views

What data structure is suitable for implementing dynamic huffman encoding and decoding on a piece of text?

Some pseudo code or resources will be appreciated.I was thinking if implementing it in form of a BST stored in an array. However,not all operations can be performed easily using this approach. I am ...
30
votes
5answers
5k views

Divide and Conquer algorithms – Why not split in more parts than two?

In divide and conquer algorithms such as quicksort and mergesort, the input is usually (at least in introductory texts) split in two, and the two smaller data sets are then dealt with recursively. It ...
3
votes
1answer
270 views

Why are there non-decidable languages? Can anyone explain me my book's solution?

Well in my book it is says that "there are non-decidable languages" And the proof is: Every algorithm is a word. Then there are only countable algorithms. But there are uncountable languages and ...
2
votes
1answer
252 views

Given a situation, and some conditions, verify is that situation is possible

Well it's a problem me and my friend had thought of, and well, haven't come up with anything to solve the following problem(I'll try to phrase it in the best way I can): Given that there are n ...
4
votes
5answers
7k views

Retrieving maximum value from a range in unsorted array

I have an unsorted array. I have queries in which I give a range and then the maximum value from that range has to returned. For example: array[]={23,17,9,45,78,2,4,6,90,1}; query(both inclusive): 2 ...
2
votes
3answers
3k views

How can you prove an acyclic graph has n-1 edges? [closed]

I'm not so hot on the maths for this but for what I understand... A graph g exists with v vertices and edges. g = (V,E); The spanning graph for this is an acyclic copy of this where all the vertices ...
1
vote
0answers
140 views

Matching two lists of data with different conventions

I have two lists of data, A and B. These lists are themselves aggregated from multiple sources, and contain typos, abbreviations not found in the other, and also lack a 1-1 mapping, but will never ...
1
vote
1answer
10k views

Quicksort and middle pivot

I am having a head ache understanding quicksort with middle pivot. I found lot of explanations about using left most or right most, but not many about a middle one. Can I safely assume these?: If ...
3
votes
1answer
163 views

Algorithm/Strategy or Data structure to capture priorities sub priorities in an app

I am working on a CMS that is starting to evolve a bit. We started off with content that had the following priorities ( columnn in the db on the content table): HIGH MED LOW. Data was fetched by ...
2
votes
3answers
186 views

What kind of algorithm could be used to produce an ordering which maximizes # of satisfied 'less than' constraints?

Let's say I have a set of items {e1, e2, ..., en}, and I also have a set of constraints {c1, c2, ..., cm}, with ci := ej appears before ek, for some j and k. I want to produce an ordering of my items ...
0
votes
2answers
457 views

Can an 81 digit number generator lead to copyright infringement? [closed]

I'm looking to write a program that will generate valid sudoku puzzles. Essentially, a sudoku puzzle is just an 81 digit number. (The blanks are zeroes.) I would then like to use these puzzles in an ...
2
votes
2answers
881 views

Transform math formula into code (line-line intersection)

I'm having hard times transforming a math formula to code. I can solve it on the paper easily, but it's hard for me to bring it into code form. Is it generally possible to bring a math formula ...
33
votes
9answers
7k views

Is the algorithm more important than the programming language?

During the current (2013) Google Code Jam contest, there was a problem that took C++ and Java people 200+ lines of code as compared to Python people that solved the same problem only using 40 lines of ...
0
votes
1answer
971 views

Puzzle solving: Minimum number of steps to achieve a goal

I have been doing some programming contest problems, and I have noticed that many of them involve something along the lines of "get the minimum number of steps necessary to achieve a certain goal". ...
2
votes
4answers
408 views

Approach to simplifying an algorithm

For completely random reasons*, I wrote some code that calculates and displays the following expression: P=1*(2+2)(3+3+3)(4+4+4+4)..(n+n...… Which is equivalent to (n!)^2 The version I wrote (...
12
votes
7answers
5k views

Generating random math expression

I have this idea running around in my head, to generate and evaluate random mathematical expressions. So, I decided to give it a shot and elaborate an algorithm, before coding it to test it. Example: ...
-1
votes
2answers
745 views

What is the best programming language to do crypto running time measurement? [closed]

I am trying to measure the running time of different crypto algorithm. e.g. how long it takes to encrypt/decrypt a block of plaintext. May I ask if C with OpenSSL is the best PL to do this?
0
votes
1answer
300 views

Creating alien symbols or signs that look natural [closed]

I was reading some Cthulhu Mythos stuff and started to think about those various signs and symbols that are used in the texts. Of course those are made by humans but point is that they look natural to ...
0
votes
2answers
228 views

How can I compute maximal area including only given integer pairs of (x,y) coordinates?

The values ​​of a function of two variables z = f (x, y), where x, y, z take integer values are stored in sql db. Calculate (appoint) the largest surface area of ​​the flat. By 'flat area' we mean an ...
8
votes
1answer
436 views

Does any know of a Algorithm that allows for a figure like this image?

Does anyone know how to create an algorithm capable of making the figure just like in the picture, when given a set of specific points (3D array)
1
vote
2answers
481 views

Can we create a program that writes out its source code?

Can we create a program that print out its source code what if we (or the program itself) compile than the new program would have the same exact functionality what the original program has? So somehow ...
1
vote
4answers
2k views

What does it mean to perform an operation “In Place” for Interpreted Languages?

Programming question: Reverse words in a string (words are separated by one or more spaces). Now do it in-place. What does "in-place" mean in the above context for an interpreted language ...
3
votes
4answers
1k views

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, ...
1
vote
1answer
386 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 ...
1
vote
2answers
2k views

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 ...
0
votes
1answer
830 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 = ...
11
votes
1answer
613 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 ...
30
votes
8answers
25k views

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 algorithm....
1
vote
2answers
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 ...
5
votes
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 ...
5
votes
1answer
1k views

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 ...
3
votes
6answers
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 ...
2
votes
2answers
826 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 ...
1
vote
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 ...
33
votes
6answers
3k views

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 ...
8
votes
1answer
470 views

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, ...
17
votes
5answers
6k views

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 ...
2
votes
4answers
4k views

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 (...
8
votes
1answer
1k views

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 ...
-2
votes
2answers
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?
7
votes
3answers
2k views

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 ...
-1
votes
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 ...
8
votes
3answers
12k views

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 ...
1
vote
1answer
210 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, ...
0
votes
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 ...
0
votes
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 ...