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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Algorithm to infer tag hierarchy

I'm looking for an algorithm to infer a hierarchy from a set of tagged items. E.g. if the following items have the tags: 1 a 2 a,b 3 a,c 4 a,c,e 5 a,b 6 a,c 7 d 8 d,f Then I can construct an ...
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2answers
3k views

Why does a proportional controller have a steady state error?

I've read about feedback loops, how much this steady state error is for a given gain and what to do to remove this steady state error (add integral and/or derivative gains to the controller), but I ...
0
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2answers
161 views

moore's law and quadratic algorithm

I was going thru a video (from coursera - by sedgewick) in which he argues that you cannot sustain Moore's law using a quadratic algorithm.He elaborates like this In year 197* you build a computer of ...
3
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1answer
87 views

An extensible logging architecture for Android?

The end goal is to have a variety of data sets that can all be graphically plotted against eachother. All data should correspond to a date, so that when plotted against each other, they show the ...
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1answer
191 views

Custom animation iOS

I have seen animation, and i can't figure out how to do something like in this video(youtube). I want to discuss how it's made. I don't think that they're using sprites. I have one idea how to do ...
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8answers
14k views

Sort algorithms that work on large amount of data

I am looking for sorting algorithms that can work on a large amount of data, i.e. that can work even when the whole data set cannot be held in main memory at once. The only candidate that I have ...
6
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1answer
2k views

Sleeping Barber Problem (with multiple barbers)

The Sleeping Barber Problem is a classical synchronization problem that many of you may be familiar with or at least heard of. It's based on the premise that a barber (a thread) sleeps when there ...
4
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2answers
587 views

How much logic can be put into an object-pooling factory class before it does more harm than good?

The main language I'm interested in doing object pooling in is AS3, which is known to need it in many cases. In the past I've always made a brand new factory class for every type I was going to try ...
2
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1answer
286 views

Algorithm to update priority ordered list where changing priority of an item is expensive

I am working against an API where I can add and update items in a list that is ordered by a priority field I can set (which need not be contiguous but must be a positive integer). Updating a list ...
2
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1answer
152 views

content fingerprint algorithm

I have a database containing just simple URLs. It is as simple as it sounds for now and URL can link to a website or a document(i.e. anything parseable to text). Now I have a simple code which ...
8
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8answers
920 views

When developing algorithms, is skipping the pen&paper phase a bad habit? [closed]

I heard many people saying that when developing algorithms you should first use pen and paper, flowcharts and what not, so that you can focus on the algorithm itself, not worrying about the ...
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1answer
9k views

Algorithm to create an TicTacToe game AI [closed]

What are the algorithms I could use to create an AI for the game TicTacToe. I have already used Alpha–beta pruning and Predictive modelling. What the other good Algorithms I can use to create this AI. ...
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3answers
1k views

What skills (technologies) get outdated slower? [closed]

It's a common knowledge that since the IT industry develops very quickly, most of the skills get outdated fairly rapidly: jQuery, .NET, Ruby on Rails, etc. They change all the time so that it is ...
3
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2answers
173 views

What would be the optimal way to solve a problem like this?

I have a problem where I have to change all the Xs in a 2D array into 0s, and I have to calculate the minimum steps (where a single step consists of changing an entire row or column) required to do ...
53
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11answers
3k views

Writing my problem solving approach on paper?

I'm a freshman Computer Science student and we just started doing some actual projects in Python. I have found I'm very efficient when I use the pen and paper method that my professor suggested in ...
22
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5answers
2k views

Can someone else patent my open-sourced algorithm?

I've written a recursive search algorithm to find the boundaries of a voxel data structure in order to render it more efficiently. I've looked around, and either it's such a simple and obvious ...
5
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1answer
164 views

Problem in Understanding Algorithm from TAOCP “Multiply Permutations in Cycle Form”

I am not able to understand one algorithm discussed in TAOCP Volume 1; Section 1.3.3 named as "Algorithm A" stated as "Multiply permutations in cycle form" while compared with the stated example in ...
6
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1answer
480 views

How can a beginner develop an algorithm for this problem?

Before I'm flamed, I'm just a beginner in programming. I have been learning Python for about 1 week by myself. I have a real problem to solve: Goal: The fastest route through a pathway. Problem: ...
4
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2answers
552 views

Deduplication of complex records / Similarity Detection

I'm working on a project that involves records with fairly large numbers of fields (~15-20) and I'm trying to figure out a good way to implement deduplication. Essentially the records are people along ...
8
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3answers
805 views

What Is The Formula for the 3 of 9 Bar Code Alphabet?

Background: 3 of 9 Barcode Alphabet A simple syntax for 3 of 9 bar codes What is the formula behind the alphabet and digits in a 3 of 9 bar code? For example, ASCII has a relatively clear ...
3
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1answer
227 views

How to solve binary labeling with graph cut?

Many literature references suggest that the binary labeling problem can be converted into a graph cut problem and solved with the max flow/min cut algorithm. I'm trying to understand the formulation ...
7
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3answers
367 views

Is there a 'design pattern' type listing of common algorithms? [closed]

Is there a 'design pattern' styled listing of common/popular algorithms anywhere? Specifically, something that has a similar format along the lines of: Algorithm Name: e.g., Quick Sort, Bubble Sort, ...
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3answers
3k views

Why are algorithms and data structures important? [duplicate]

It seems like a lot of university-level computer science programs and programmer job interviews focus heavily on algorithms and data structures. I'm curious as to why universities and employers put so ...
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1answer
111 views

Algorithm for determining the order of property resolution

I have a list of properties, that are bound to some string expression: property z, expression '[x] + [y]' property x, expression '[y] + 1' property y, expression '1' So to solve z, I need ...
2
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1answer
169 views

Strategy for normalising and interpreting location data

I'm a bit stuck with a problem involving the normalisation of location input data from the user (which comes from a third party). Aim To logically breakdown and interpret the user location input ...
2
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0answers
208 views

Generate complex (non-convex) polyhedron UV mapping

I need to find an approach to the problem of generating texture maps for non-convex polyhedrons without using a design tool like Maya. Specifically, I am mapping simulation results data onto a 3D ...
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1answer
159 views

Algorithm analysis refresher help

I haven't touched algorithm complexity stuff in quite a while, so I am trying to do a refresher. I am trying to figure out the number of steps in the following for loop. for(i = 0; i < n; ...
3
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2answers
596 views

Which of these two shuffle algorithms is more random?

Which of below two shuffle algorithms (shuffle1 and shuffle2) is more random? public final class Shuffle { private static Random random; public static void shuffle1(final Object[] array) { ...
2
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1answer
244 views

Programming puzzle with constant selection

THE QUESTION: There is an event where there are N contestants. There are three tasks in the event: A,B,C (say). Each participant takes part in the events in the listed order: i.e a contestant must ...
8
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1answer
743 views

What's the best way to learn nature-inspired algorithms? [closed]

I completed the Machine Learning course (Stanford) and got very interested, also after some research, I decided that I'd like to learn nature-inspired algorithms. I've found some resources like: ...
0
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1answer
334 views

help in theory regarding prefix_suffix_set

I found this question at codility.com, but I don't understand the question. Can you help me figure out what do they want? I am more interested in the theory than a code. A non-empty zero-indexed ...
2
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1answer
118 views

Storing different algorithms and using them for demonstration

I have an app for creating simple graphs (the kind with vertices and edges) and then using different algorithms on them (BFS, DFS, topsort, Prim's etc) for demonstrating how they work. I'm now ...
0
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1answer
128 views

Algorithm for compression of a dictionary (words and definitions)

The theoretical situation is this: Let's say that we have a digital dictionary (by which I mean a traditional list of words and definitions, not an associative array). For the sake of simplicity, ...
0
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3answers
737 views

Program/library to match string patterns [closed]

I've city names, like Newyork. Somebody may misspell it and write it as Newyoork. I want an algorithm or library which can match such patterns with some confidence level. Any idea how to do it or if ...
3
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3answers
563 views

Finding an object on an infinite line

Question: There is an infinite line. You are standing at a particular point you can either move 1 step forward or 1 step backward. You have to search for an object in that infinite line. Your object ...
3
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1answer
226 views

How does Mercurial determine which changesets I need when I pull?

This is a question about the internal workings of Mercurial. I vaguely remember a fellow programmer explaining to me how mercurial works out which changesets differ between two repositories and that ...
3
votes
1answer
190 views

Algorithm to arrange objects so that the total length of edges between them is minimized?

We are given a list of edges between a set of N vertices. There are atmost three edges joining a vertex. We have to arrange all the vertices on a straight line with the positions numbered from 1 to N ...
2
votes
2answers
374 views

When is a code considered tight and how does it increase efficiency of the code?

I have read many times that insertion sort has tight code and hence the hidden constant factor in its asymptotic complexity is smaller. I just read yesterday that quick sort has tight code just like ...
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3answers
577 views

Sort an array in a specific order - not ascending/descending

I'm working on an algorithm that works best if the inputs are passed to it in a particular order, so I want to sort them that way. The difference is drastic enough for me to consider re-sorting the ...
3
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1answer
239 views

Finding maximum number of congruent numbers

Let's say we have a multiset (set with possible duplicates) of integers. We would like to find the size of the largest subset of the multiset such that all numbers in the subset are congruent to each ...
5
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3answers
2k views

Parsing scripts that use curly braces

To get an idea of what I'm doing, I am writing a python parser that will parse directx .x text files. The problem I have deals with how the files are formatted. Although I'm writing it in python, I'm ...
17
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4answers
6k views

In pseudo code what does := mean?

The section entitled Algorithmic Implementation has the following code: // Return RC low-pass filter output samples, given input samples, // time interval dt, and time constant RC function ...
5
votes
1answer
729 views

Hashing Algorithm: Deleting an element in linear probing

While using Linear probing method to implement hashing, when we delete and element, the position of the deleted element is declared as a tombstone/ mark it as deleted. Why can't we just shift all the ...
1
vote
1answer
955 views

Matrix Pattern Recognition Algorithm for a 2D space

I have a picture that I elaborate with my program to obtain a list of coordinates. There is a matrix represented in the image. In an ideal test I would get only the sixteen central points of each ...
5
votes
3answers
360 views

Algorithm to pick user

I need an algorithm for picking a user. Users are identified by letter {A, B, C, ...} and are ranked by number {1, 2, 3, ...}. Rank is the degree of likelihood to be picked, so a rank 2 user is ...
2
votes
1answer
101 views

Sorting with continous input

I'm designing (not writing, yet) a task scheduler system for a complex video game. The rest of the program passes it objects containing a function and some metadata including an estimation of how much ...
3
votes
4answers
905 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, ...
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2answers
115 views

Calculate transfer time while accounting for loss of conductivity and speed over circuits [closed]

So based on my limited understand of how computers work I derived the following question. As you transfer things over circuits the circuits heat up. As they heat up they lose conductivity and ...
0
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2answers
222 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 ...
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2answers
352 views

How fast should a Python factoring script be?

Just how efficient is "good enough" for all intents and purposes? I wrote a script to simply list off all numbers that divide into an input, x, as pairs (i, n//i) and was just curious how efficient I ...