# Tagged Questions

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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### Generating sort keys when reordering items

We have a number of items which the end user will be able to organize into a desired order. The set of items is unordered, but each item contains a sort key which can be modified. We're looking for ...
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### Generate a unique random 4 digit number from another 4 digit number [on hold]

I have a database that has two columns. The first column is an index, the second is the path to a data file. There are two types of data files, X and Y. These data files are then processed and graphs ...
421 views

### Is it ethical to adopt other programmer's algorithms?

Imagine I find a completely new algorithm to compute the square root of a binary number (simplification of real scenario) on an internet forum that was an original creation. Is it ethical for me to ...
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### How do I split up match-ups into rounds such that each team only plays once in each round?

I have twelve teams represented by integers 0 - 11. Given 24 predetermined match-ups, I need to place the match-ups in 4 rounds such that no team plays twice in the same round. This is similar to a ...
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### Why does the last phase of Irving's Stable Roommates Matching work

Pertaining to the Stable Roommates Problem and the algorithm developed by Robert W. Irving. There are two (sometimes broken into three) phases in which we may come to a stable pairing of everyone in ...
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### Which hashing algorithm is best for uniqueness and speed?

Which hashing algorithm is best for uniqueness and speed? Example (good) uses include hash dictionaries. I know there are things like SHA-256 and such, but these algorithms are designed to be secure,...
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### Algorithm to generate all paths between two vertices of a graph in F#

Following a functional programming approach (no mutable data structures, recursion, etc) I have written a script in F# to generate all paths between two vertices of an undirected, unweighted graph. I ...
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I need to find an optimal distribution of some matching tasks on multiple jobs; each job is limited by a maximum workload and the grouped tasks should maximize the workload within the same job. ...
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### General way to convert a loop (while/for) to recursion or from a recursion to a loop?

This problem is mainly focusing on the algorithm, maybe something abstract and more academic. The example is offering a thought, I wanna a generic way, so example is only used as to make us more ...
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### Algorithm for seating Zoombinis on Captain Cajun's ferryboat?

I've been playing the rerelease of The Logical Journey of the Zoombinis recently, and trying to implement some computer algorithms that can solve the various puzzles. I'm stuck on how to approach the ...
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### How to approach hours forecasting

I need to forecast budgeted hours for 2 departments to help them schedule staff as currently the best they can do is just wing it. When we receive a job proposal I'll have the person submitting the ...
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### What algorithm or program does Java use for arithmetic?

I was looking at bitwise ways to multiply and add numbers without using * or + operators. But I want to know that it might be possible that java may already be using a better approach underneath. I ...
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### Pitch/Time Shifting of a PCM byte array

I am searching for a universal algorithm that shifts pitch and time while keeping the sample rate. (I am trying to program a sound generator (sine, triangle...) as an exercise) I just want to squeeze ...
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### How can I filter my coordinates system?

Following up with this, I have a bunch of coordinates and I draw them on a bitmap image as a coordinate system. Now, I would like to get rid of all the noise, and filter coordinates to give a "clearer"...
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### Getting a stateless time-based index out of overflowing timer

I'm currently working on an Arduino project where I need to keep track of entries for a certain amount of time, in this case, 30 days. Our company will attempt to sell this product to cities and ...
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### Need a solution for data filter problem

Problem statement: I have a input with multiple key value pairs and a list tasks stored in database with filter object. As an output I need a list of tasks matching the input values based on task's ...
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### Efficient way to calculate how many items to destroy if each has a 70% chance to be destroyed

We start with a variable that holds an integer for the "number of items" that we have somewhere, somehow. Then, the algorithm is applied: each one of those items have a 70% chance to be destroyed. ...
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### How does Pearson hashing compare with other non-cryptographic hashing algorithms?

FNV-1, Murmur2, and DJB2 are examples of non-cryptographic hashing functions used in actual applications (see Which hashing algorithm is best for uniqueness and speed?). These are all similar in that ...
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### Algorithm for lines comparison

I'm working on the import of land-use data into Openstreetmap. Unfortunately I've encountered a problem that has delayed my time table. Take a look at the picture below: the red line is the main road ...
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### Split k sets to 2 groups of sets

Given k sets ,each contain several elements . I want to split them to two groups , the first group contains m sets ,the second group contain n sets , m + n = k . Let w1 be the sum of the weights of ...
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### Algorithm for ranking a list of items

Given a list of items, what's the most efficient way of ranking those items with the least number of comparisons? Is there a name for this type of algorithm (that way I can focus my search)? Also, is ...
122 views

### Decomposing into multiple of divisors

I have a number x. I know its prime factors and their multiplicity. Does anyone know an algorithm that decomposes it into all possible combination of its divisors (without respect to order)? E.g. x=...
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### Extract All Possible Paths from Expression-Tree and evaluate them to hold TRUE

This is a follow-up question of my previous one: http://stackoverflow.com/questions/38421950/better-class-structure-for-logical-expression-parsing-and-evaluation Brief introduction: rules as ...
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### Dynamic-programming matrix exercise

I'm practicing with dynamic programming and I'm trying to solve this exercise http://www.geeksforgeeks.org/collect-maximum-points-in-a-grid-using-two-traversals/ But I can't understand how to use ...
239 views

### Dynamic Programming - Largest arrangement of bookcases

I'm trying to solve a problem, so I'm not looking for code, but for similar algorithms so I can solve it myself. I am given n bookcases each with a size amount of books inside. I am to move some of ...
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### Extract significant locations from GPS readings

I'm writing an app that continuously monitors user location 24 hours a day using a mobile phone with readings every 5-30 mins (about 50-300 readings a day). How do I cluster readings and extract user ...
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### How to shift elements within a matrix?

I have a grid of objects that occupy cells in a grid. Basically similar to android launcher - with icons and widgets and whatnot, because that's what I am building. To keep track of which cells are ...
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### How to “de-dupe” similar lines (detected using the Hough Transform as rho/theta pairs)

I'm trying to identify an object (a cube) in a set of photos. Using Canny/Sobel/Hough I've managed to get the photo down to a set of lines that are pretty accurate; however if I plot these lines on my ...
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### Recursion in Merge Sort algorithm. How is it obvious to use this type of recursion?

I dont want to put too much code so I'll just put the code that involves recursion. This algorithm is fairly well known so I think everybody knows the basic code. void mergeSort(int array[], int l, ...
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### Grouping algorithm

We've developed an algorithm that depending on the check-in time of some workers and their living place, calculates the way to group them into some vehicles and the route which must be followed by the ...
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### Optimal Simplification of Transposition Products

I am looking to take a product of a large number of transpositions, and boil it down to a smaller number of products. I have the following code, and would like some input on efficient ways to boil ...
101 views

### Place circle such that it overlaps the most possible other circles

Given a list of circles (each with parameters (x,y,radius) ) I want to place another circle with a fixed radius such that it overlaps the maximum possible circles from the list of circles. As long ...
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### Finding unique tuples list of options

I'm having a bit of hard time finding a solution to the following problem. I need to find tuples of (a-c, 0-2) such that if I make a choice with one letter and a key I can't select it again. Example: ...
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### How to get the average of how many occurrences of numbers [closed]

I have code that looks at numbers 1 - 5, and counts how many occurrences of those numbers appear in an algorithm. What is an algorithm for finding the average number of 1 - 5 by counting the ...
280 views

### How to solve this seating problem?

I was solving a seating problem whose solution seems trivial but I am not able to get it. The problem states in short that we have to seat n (even) students in n/2 rows where students are labelled ...
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### Which algorithms/data structures should I “recognize” and know by name? [closed]

I'd like to consider myself a fairly experienced programmer. I've been programming for over 5 years now. My weak point though is terminology. I'm self-taught, so while I know how to program, I don't ...
532 views

### How to find hard to misspell given names?

Here is a question that I believe could be solved with some data mining and a sophisticated algorithm, but I don't quite know how. Any pointers as to what data sources to use and what algorithm to ...
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### How to implement to flood fill algorithm on multiple machines?

I have a large image distributed over multiple machines for which I need to implement the flood fill algorithm used in MS Paint. I am able to do it with a single machine but what approach must be ...
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### Swapping variable values without creating a new one

Recently, I was faced with a question that asked me to swap variable values without creating an extra variable. i.e. A = 10, B = 20. How store 20 to A and 10 to B? The solution is: A = A + B #...
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### Finding and counting equal substrings in a set of strings

I'm thinking about a way of finding similar parts in Strings. I have a set of strings of variing length i.e: The quick brown fox jumps fox force five the bunny is much quicker than the fox is ...
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### Sort numbers into three groups s.t. their sums are close to a certain value

I have a list of numbers (let's call it L) and I need to split this list into three groups (A, B, and C) such that the sum of the numbers in each group (sum(A), sum(B), sum(C)) is as close as possible ...
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### What is a helper? Is it a design pattern? Is it an algorithm?

Maybe a little tongue-in-cheek, but as I can't find this answer anywhere through Google, so to ensure Programmers Stackexchange has the answer: What is a helper? I have seen the name being used ...
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### Implementing CMA-ES

I am attempting to implement the CMA-ES optimization algorithm in my favorite language (using the example code here as a guideline), but I need help solving a problem I am having. To test the ...
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### Formalising algorithms - Greek symbol uses/sources [closed]

I am looking to formalise an algorithm that I have created, however, I am having trouble knowing how to correctly use Greek symbols (such as Epsilon, Omega etc.). Are there any guides/standardised way ...
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### Modelling a complex schedule of work

I've got a real-world problem that I'm trying to represent and automate. I've simplified and abstracted it down to the following: There are n places of work (P1, P2, ..., Pn). Each place, Pn has a ...
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### How to use the 0-1 knapsack problem with more than one bag

The 0-1 knapsack is a well-known algorithm that solves the problem of finding the maximum profit P of putting some of n object( each of weight w and profit p) in a bag of capacity W. How can I use ...
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### Fast, lossless compression of a video stream

I have a video coming from a stationary camera. Both the resolution and the FPS are quite high. The data I get is in Bayer format and uses 10 bit per pixel. As there's no 10 bit data type on my ...
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### All minimum cuts in flow network [migrated]

I'm trying to prove that for a flow network, maximum flow f, and each minimum cut S that f(S)=c(S). Max flow min cut promises that there exists a cut where f(S)=c(S); I want to prove that given ...