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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Matrix multiplication range queries

I have a huge list of matrix i.e A = {M0, M1, M2 .. Mn}. I have a task to find the product of all the matrices in a given range {x,y} i.e Mx * Mx+1 * Mx+2 ... * My. I would like to know if there is ...
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24 views

Create unique buckets for stream of entities based on constraints on the entity attributes

I have stream (magnitude 10s of millions) of entities, say Item which is modeled as below: class Item { String id; Double price; Double profitPercentage; Country originCountry; Country ...
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1answer
149 views

Complexity of recursive calls

my brain is a little stuck as I am trying to compile an example for my blog. I am presenting an algorithm that draws a number from an array, adds it to a sum and calls itself recursively. func solve(...
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2answers
142 views

Check if list has a list of values

I have been trying to figure out an efficient algorithm that can check if a list of values contains a list of values. Both lists are sorted in ascending order. For example: Check if var ...
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1answer
57 views

Mapping match-up combinations into an integer

First of all, I want to say I wasn't sure if I should post this here or in math.stackexchange but I think the question is too programming-related to belong to the latter community. Definetly not a SO ...
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77 views

Find largest subset where two elements share a property

I have a set of numbers S and I want to find the largest subset S' such that for any two elements x,y in S' property(x, y) == True in_relation(x,y) == True. How could I find it? Bruteforcing is an ...
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1answer
42 views

Why use last column of Burrows-Wheeler-Transform

The Burrows-Wheeler-Transform takes a string with length n, creates a matrix with n rows by shifting this string one position to the left for each row. Then the rows are sorted by the first column in ...
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58 views

How to solve min cost max flow program with brute force

I have a use case where I need to solve min cost max flow problem for nodes < 5. Implementing Cycle canceling or some other min cost max flow problem seems like a over kill for this, is there some ...
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1answer
157 views

How to implement k-means algorithm on RGB Images?

I want to apply the k-means algorithm on an RGB image data-set. I don't know how to proceed. You can mention basic step by step flow to proceed. I do know basics of Image Processing & OpenCV.
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51 views

Are there any generic algorithims or Python functions to help find the longest item in a JSON document?

I am trying to log a JSON error message to Google's Cloud Logging platform. Unfortunately, the maximum size message you can log is 8000 bytes and some of the JSON documents I want to log are larger ...
0
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1answer
315 views

One font OCR for meme images

I'm coding an Optical Character Recognition specifically for the Internet meme images. This is a school project and it should be coded in C. I'm currently having trouble with the method/algorithms I ...
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2answers
62 views

How to represent complex permissions system in single hash or set of characters?

Eve Online, a game I used to play, had an interesting "permissions" system for account interactions with other apps. The permissions encompassed dozens of individual permissions, each under a ...
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90 views

Unable to Solve Dynamic Programming

I had an assignment on dynamic programming due last night, but I had to turn it in unfinished because i could not understand how to solve the last problem: The state wants to monitor traffic on a ...
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129 views

Which 3D algorithms does Windows 10's “3D Builder” application use?

Windows 10 ships with "3D Builder", a Universal App that contains utility functions to prepare STL, OBJ, 3DS, and other files that represent geometries for 3D printing. The utility looks like this: ...
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1answer
139 views

Best two-way compression algorithm for 32-bit numbers

I need to compress an id for marketing campaigns. The current campaign id is 32-bit integer but obviously this is too long for a customer to type by hand. I would like to compress this to minimum ...
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3answers
144 views

How do I generate multiple hashes that can be resolved to a single value?

I need multiple "random" URLs that just mask the original URL, i.e.: /ABC /CBA /CAB All resolve to /6 I came up with matching a letter to a number and then you can sum them to the single value. A ...
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1answer
98 views

tiling algorithm for maximum size of equal-sized tiles

I'm trying to fit an arbitrary number of HD videos on screen so that they all have equal size, maximizing the size of the videos, with no scrollbars appearing. Given N number of tiles of equal ...
5
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1answer
115 views

Algorithm to find span intersections in a sorted set

I have a set of items strictly ordered on time. Each item can either be single (no Next, no Previous) or part of a span (with either 1 or 2 further endpoints). For example in the picture A is part ...
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5answers
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Is there any good search algorithm for a single character?

I know several basic string-matching algorithms such as KMP or Boyer-Moore, but all of those analyze the pattern before searching.However, if one has a single character, there is not much to analyze. ...
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154 views

How to find complexity of T(n) = 8T(n/2)+n^2.93(log n)^93?

I believe we have to use a variant of master theorem...can someone suggest me how to find complexity of such equation which doesn't directly fit into Masters theorem.
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38 views

Partition edges into areas

If I have a series of edges that branch and curve, such as in a road network, is there an algorithm that will identify the areas (defined by sequence of geographic points) defined between those lines? ...
3
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1answer
186 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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1answer
151 views

Algorithm to generate all sets of m points in n x n x n cubic lattice which are unique under symmetry

I am implementing an algorithm which is going to be quite computationally complex, and want to try to make sure I'm not doing unnecessary work. There is an n x n x n cubic lattice, e.g. if n=2 this ...
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2answers
130 views

Design for autocompleting words in search engine?

I'm trying to implement an autocomplete feature for a search engine. I have a database of words(stemmed) that occur in the documents that I have for users to search. What I am thinking of doing is: ...
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2answers
137 views

Algorithm for finding all empty tiles in rectangular grid?

I have a rectangular grid of square tiles, some of which are blocked/filled. I start at a random tile inside the grid with the blocked tiles, randomly placed. I can turn in 90° steps and check whether ...
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52 views

Restricted randomization of a binary vector

Suppose I have a binary vector of sample size N with each of the two possible values (e.g., 0 and 1 occurring equally often). For example, if N=10, the binary vector is: 0 0 0 0 0 1 1 1 1 1 Suppose ...
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1answer
62 views

Keeping track of the number of nodes in the subtree in black and red trees

I was wondering, if I have a black and red tree and I want to keep track of the number of nodes in the subtree, what is the most effective way to do so? I mean how do I work with these values while ...
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1answer
189 views

Finding all possible ways of inserting a pattern into a string

I've been thinking about this problem for a while, and I can only find a recursive solution but I'm feeling that there is a dynamic programming way to do it, I just can't figure it out. Is this a ...
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2answers
180 views

How to match up courses with requirements

I have a list of courses taken by a student, as well as several requirements. Each requirement consists of a list of courses that fulfill that requirement and the number of such courses that must be ...
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0answers
46 views

List all intervals made by inherited array of intervals

i have a grading system which works like this: You have a array of intervals with grades: [9, Inf) => A; [7, 9) => B; ... (-Inf, 1) => F But you can create also inherited grading system ...
3
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1answer
155 views

Neighbourhood points (2d)

I have a 2d coordinates system with some points on it, like this one: Now I am looking for an algorithm (or just some approach) to find neighboured points. So, if you have the coordinates of one ...
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1answer
75 views

Determine what to draw based on neighbour tiles?

I have a tilemap and I want to add walls to it. I painted 16 images, one for each possible combination. For example: A lone wall tile would get a image that has walls around. A corner would get ...
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132 views

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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1answer
143 views

How to find the closest vector to a given vector?

Let's say I have several points / vectors (in 2D to keep it simple, but could be of any dimension) [x1, y1] [x2, y2] [x3, y3] .... [xn, yn] If I pick some point [x', y'], how do I ...
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2answers
105 views

Generate pips on a die based on value

Is there an algorithm to generate the pips on a die or domino? I know that there is usually an odd number of columns and even number of rows (unless the max number of pips is not a perfect root). ...
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2answers
513 views

Why do textbooks use pseudocode rather than real languages?

In colleges and in algorithm textbooks, it is quite common for the teacher and author to explain control flow in pseudo-code. With the advent of more expressive languages like Python and Haskell among ...
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2answers
121 views

Algorithm to detect if a list of strings need delimiters

I need to write a function to detect if a set of strings needs delimiters when concatenated in any order. For example, the strings ("A","B","C") do not need a delimiter: "ABCBB" -> ["A","B","C","B"...
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1answer
45 views

Patching data by identifying and copying repeating pattern

I have a dataset sampled with a specific pattern (timestamps). The very first repetition of the pattern is damaged, meaning that the values are nonsense. To exemplify, my data looks like this: data = ...
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1answer
32 views

Sorting algorithm for Provides/DependsOn objects

I have a set of type rewriters, each modifies a given C# type in a different way. Examples are: Add the XYZ attribute to each property of the class Add an ID property Add two properties and some ...
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2answers
197 views

Merge sort and O(n log n) mystery

I read every explanation here but still not convinced. I think mergesort is n * n and I know I am wrong but not sure where. Here is what I think: Suppose we are sorting 8 elements and this is the ...
3
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5answers
256 views

How to calculate winning chances of one poker hand against another? [closed]

My question relates to Texas Hold'em Poker. But I believe it will be the same algorithm for any kind of poker game. So let's consider two hands: AJo and KQo. I can use online calculator and find out ...
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1answer
205 views

What is the meaning of “static” in pseudo-code

This is a pseudo-code from "Artificial Intelligence: A modern approach" function Table-Driven-Agent(percept) returns action static: percepts, a sequence, initially empty table, a table, ...
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1answer
107 views

Find missing number in sequence in string [closed]

I have a string that contains numbers in sequence. There are no delimiters between numbers. I have to find missing number in that sequence. For example: 176517661768 is missing the number: 1767 ...
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1answer
97 views

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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1answer
27 views

Extract the main entity from a body of text for text categorisation?

I'm trying to categorise products based on various fields of data. I've had some success just matching search terms in the product names, but this naive approach doesn't work when it comes to larger ...
0
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1answer
131 views

Algorithm to get all possible forms of a word with varying suffixes [closed]

I'm writing an application in javascript where given a word, I need to get all the possible versions of the word with the suffix being the difference between each form. For example: "sponsor" should ...
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4answers
211 views

Selecting a CPU or microcontroller needed for a given software application?

Say I had a software algorithm (for example, an FFT), and I need it to process (n) amounts of data in (t) milliseconds. This is a real-time task written in C. There are a lot of CPUs out there, and ...
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1answer
55 views

Considerations when making data structure and algorithm choices [closed]

What are some reasons you may choose a worse runtime algorithm? And what are some advantages of a linked list vs a hash table/array where access is constant time.
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53 views

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 ...
2
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1answer
263 views

Word game algorithm

Back in the days of 8-bit machines there existed an educational word game. I have no idea what it was actually called but for the sake of this question (since it involves pyramids) let's call it ...