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 chain together points in an array

I have a series of points with lengths and rotations like this: I need to create separate chains from points whose lines overlap but I’m having real trouble doing this efficiently. I have an array ...
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86 views

Confusion in understanding the theorem on Amortization

I was reading a book on Algorithm Analysis by Micheal T Goodrich. I came across amortization technique and I got struck in understanding the proof of theorem. I am putting the theorem and the proof ...
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3answers
271 views

Best practices for geolocation

We are writing a flight search engine. We want to pre-fill the departure airport for mobile users with the closest one to their location. To do that, our plan is to Find a list of airports with ...
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63 views

Find common ancestor

Given X number of leaves (the ringed leaves in the picture) in an unbalanced tree with depth aroun 100-1000 and total number of nodes around 15 000 000. I'm looking for the first common ancestor for ...
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72 views

Creating fast, realtime dialogue search for television scripts

We have a database of television scripts and we'd like to search it, getting results as we type. We often remember words or snippets of dialogue but can't remember exactly what was said or what ...
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2answers
77 views

Distribute load evenly across many cycles

I am looking for a solution that is fast and still readable. I have to do this in C but the code will be static in the end, which mean I could use any tool to generate it. I have a task which runs ...
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3answers
119 views

How to convert this recursive problem to iterative? Line Simplification algorithm fails to run due to Maximum Recursion Depth being hit

I am implementing the Douglas, Peucker's Line Simplification algorithm in Python. I started with this implementation. However, it fails to run in Python due to Maximum Recursion Depth being hit. How ...
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44 views

Stable, Hash Based Symmetrical Difference

A lot of thought went into the implementation of the set algorithms in LINQ: Distinct, Except, Intersect and Union. They guarantee that the items are returned in the same order that they appear in ...
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90 views

Notation/Meta Language To Express An Algorithm

I need to learn a notational language, so I can express and possibly prove the correctness of what I believe to be a complicated algorithm that distributes a credit adjustment across multiple water ...
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137 views

Permutation tests for large sequences

I would like to perform a permutation test on a particularly large data set, i.e. around 4 million entries. Basically, I need to get some number of random permutations of this data set. Usual way to ...
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1answer
83 views

How to define the motion path of one object on a surface of the other one?

I have an uncommon problem. There are 2 3D objects, which are represented by arrays of vertices and triangles (.stl files). Each of them contains a big enough amount of vertices: 1-10 mln ones. The ...
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133 views

Programming a promotions engine [closed]

I am trying to implement a promotions engine for an e-commerce application and I want to figure out how such engines work especially in situations like the following. Buy X Items from Category A ...
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2answers
179 views

Sequentially/parallel algorithm for extracting blob outer perimeter/contour length

I have labelled the connected components in a binary image and found their areas and bounding boxes. The components are not necessarily filled, and may contain holes. I wish to identify the component ...
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1answer
1k views

I know JavaScript really well, but i bomb coding interviews [closed]

So I'm currently on a hunt for a new position as a Front-End Developer. I know JavaScript very well and can wax poetically about Closures, Currying, Prototypal Inheritance, Design Patterns, App ...
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2answers
83 views

An algorithm for finding subset matching criteria?

I recently came up with a problem which I would like to share some thoughts about with someone on this forum. This relates to finding a subset. In reality it is more complicated, but I tried to ...
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2answers
266 views

Which algorithm is faster? [closed]

I'm creating a small game, where the computer generate pseudo random number in give range, and the user have to guess it. I also made the option to play computer vs computer. I mean the computer ...
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2answers
89 views

Algorithm to reverse engineer permutation [closed]

I have a sequence of permutations formed using these strings: "A", "BC" and "D". The permutations are: BCAD ABCD BCDA DABC ADBC DBCA Now I need to reverse engineer this; i.e. I have a text file ...
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1answer
177 views

How to create an algorithm for determining Boolean Tautologies

So i am right now exploring some topics in a proof course and it occurred to me to try to create a boolean tautology solver. I would like an algorithm that is more efficient than brute force. Problem ...
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116 views

Dynamic programming in Bin packing

Problem: Given a list L of objects of possible sizes from set S={1,2,4,8} and unlimited supply of bins of sizes 16 each and we have to use minimum possible numbers of bins to pack all objects of L. I ...
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5answers
721 views

Print the next smallest from 2^i * 5^j where i,j >= 0

I was asked this question during a technical phone screening recently and didn't do well. The question is included verbatim below. Generate {2^i * 5^j | i,j >= 0} sorted collection. ...
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2answers
206 views

What's the shortest generating one-way hash algorithm?

I have a 24 character long id which is guaranteed to be unique. I would like to shorten that to 7-10 (or even shorter) characters long. If I generate an short id randomly then I would have to check ...
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1answer
163 views

Algorithm for rating books: Relative perception

So I am developing this application for rating books (think like IMDB for books) using relational database. Problem statement : Let's say book "A" deserves 8.5 in absolute sense. In case if A is ...
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139 views

Dividing 2D grid to most efficient search

Requirements I have Grid of unlimited size (I don't and can't know what its size) There is Object that should be placed on the grid, every object have hes stream distance (in other words: range, ...
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90 views

Ensuring submitted hiscores are not fake

I have a small game that I would like to keep track og global hiscores for. The basic is simple: username and score is submitted to a server for storage and later polling. However how do I ensure that ...
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70 views

Decrease probability of picking a list's item based on its index

I have a list of sounds that are to be played when the user presses a button. For now I just generate a random number within the range of the list and just pick the sound with that index. (I also ...
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1answer
152 views

Traverse a matrix using a linear index to get an evenly distributed values sample

I'm looking for an algorithm idea on how to traverse a matrix using a linear index while avoiding row/column based traversals to get a more diverse distribution of values. To understand this better, ...
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124 views

GSP Algorithm explanation

I've been trying to implement the GSC algorithm in C++, however I need help with clarifying the definition: http://en.wikipedia.org/wiki/GSP_Algorithm GSP Algorithm makes multiple database ...
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58 views

Weight based mapping algorithm

I am writing automatic assignment of tasks to the users. Every user has a weight (integer) and tasks should be distributed to the users according to their weights. For example I have 10 tasks and User ...
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3answers
179 views

Given known inputs and outputs, can we generate candidate functions that will map the inputs to outputs? [closed]

I've run into a problem where I have a set of inputs, as well as a couple known input-output pairs. I am interested in the output, but in order to get that, I need to figure out how the input is used ...
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1answer
131 views

Identify algorithm for my resource allocation needs

I'm trying to automate a task and I lack the right vocabulary to look up the correct algorithm. It really feels like a common problem that has likely been solved many times before. All I'm looking ...
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46 views

Equidistant polygons

Consider these polygons: For reasons of simplicity I only consider triangles or polygons with 4 vertices. These shapes are specified by the vertices, the output of the program should be modified ...
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680 views

What is a helper? Is it a design pattern? Is it an algorithm? [closed]

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 see the name being used everywhere ...
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0answers
66 views

Can sequence alignment algorithms be used for search implementation?

Hi I want to implement a search on a website which includes imperfect search results. Meaning, if the search term is misspelled or slightly different from a 100% match, the function should still ...
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1answer
176 views

Calculate reachability of one point from another

I have an array which stores a set of positive x coordinates in sorted way, say arr={1, 4, 5, 9, 12, 45} etc. And I have a maximum distance k which I can go from one point to another point let ...
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135 views

An algorithm for reconstructing a graph from its shortest path information?

I have some shortest path data for a graph. Can I reconstruct the graph itself from this data? More precisely, I have a boolean (0/1) matrix for each vertex v in graph (V, E). Matrix element [s,d] is ...
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1answer
94 views

Does parallel mergesort run differently on mesh vs linear array of processors?

I'm currently taking course on introduction to algorithm and I came across the parallel mergesort algorithm. My question is: Is there any differences in the algorithm plan if it runs on a 2d mesh ...
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2answers
281 views

Which algorithms do I need to look into?

First things first: I need to apologize in advance about the bad choice of title for this question, but I really couldn't come up with something meaningful. I'm actually looking for suggestions as to ...
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170 views

An algorithm for finding converse duplicates of ordered pairs

Given an array of ordered pairs of values, is there a well-known algorithm to find converse duplicates? [Converse meaning the same values, but in the opposite order.] That is, given ...
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197 views

Reduce a list of IPv4 to lowest common CIDR

I have a long list of IP addresses that show some pattern of closeness Example: XX.249.91.16 XX.249.91.21 XX.249.91.32 XX.249.91.160 XX.249.91.165 XX.249.92.15 XX.249.92.25 ...
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1answer
238 views

get all the combination of a given set of numbers [duplicate]

I m trying to get the possible combinations of a given set of numbers say for example 123 The possible combinations would be 123 132 213 231 312 321 For this i have written a code as below - ...
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Algorithm for percentage without knowing total number

Suppose there are n lines for a hotline. Whenever a customer calls the hotline, the call is forwarded to one of the n lines. And I want to assign percentage of calling to each of the n lines. ...
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427 views

Is Microsoft Solver capable of solving such complex scheduling problems

I'm writing a application that will decide the scheduling plan for a few dozen people according to their occupation (role) and availability (week day and hours). I've used a excel spreadsheet to help ...
3
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2answers
77 views

Trivially Sortable Encoding for Arbitrary-Precision Decimals

I'm looking for a reasonably(*) space-efficient way to encode arbitrary-precision decimals (e.g. BigDecimal), such that when sorting the bit-pattern of the encodings lexicographically, the numbers ...
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40 views

Generating all the words accepted by a deterministic finite automaton [duplicate]

Imagine you've got a finite deterministic automaton A defining some finite regular language L, consisting of N words. The first question is: how would you determine the number of words N? Then, I ...
3
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1answer
101 views

Defining a random “safe” path for a game character

I am writing a game in Java and it can be likened to the recently popular game "Flappy Bird" in the sense that the character moves up and down and the users touch and must avoid the obstacles. The ...
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289 views

problem on calculating Big O complexity

i have this function on which i have to calculate the time complexity with the Big O notation: public void print(ArrayList<String> operations, ArrayList<LinkedHashSet<String>> ...
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1answer
103 views

Random forest ML algorithm suitable for use on cluster based HPC?

I need help in identifying a better algorithm. I have developed a script using pythons scipy package to analyse a rather large model that I wish to solve. The model contains over 12GB of data ...
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64 views

Adding a minimum rectangle overlap threshold

I have a function that works perfectly for detecting whether or not r1 overlaps with r2: boolean overlaps( Rectangle r1, Rectangle r2 ) { return r1.x < r2.x + r2.width && r1.x + ...
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44 views

Matching weighted unbalanced Bipartite graph

I am looking for a way to solve an assignment problem, but I am having some problems finding the correct algorithm to use. I have 2 list of nodes A and B, and in my problem may the length of A not be ...
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93 views

How to create a scoring system with time and correct answers for a game?

o create a scoring system with time and correct answers for a game? up vote 0 down vote favorite I have a small mobile quiz game, which consists of 30 questions, and a timer which starts from 0 ...