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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Should an algorithm handle invalid inputs and can it have hard-coded paths for certain input data? [duplicate]

I have certain preconditions on input data and I need to design an algorithm for that data. Should I also handle invalid preconditions? Also is it normal that my algorithm will work only for a ...
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1answer
264 views

How important is maths depending on what your coding? [duplicate]

Possible Duplicate: What does mathematics have to do with programming? How often do you have to solve pure mathematical or algorithmical problems? I heard that math can be very important in ...
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263 views

Find 'Connected Components' in undirected, unweighted graph coded as a 2d array

Given an undirected, unweighted graph coded as a 2d array, how can I find the number of different connected components? Example There is the following 2d array (I'm not putting any brackets to ...
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1answer
271 views

What is a lattice parser?

My friend asked me for help with his task: "Redeem a lattice parser with any programming language" - the problem is that he can't clearly explain me how the lattice parser should work. I've tried to ...
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1answer
111 views

How to compute data for charting?

I'm building a charting component that displays data directly from the raw data records. It should be able to filter data (subset) and then perform some rudimentry maths on the data (sum, avg, etc). ...
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2answers
1k views

Exercise 3.6: Skiena Algorithm Design Manual

I am preparing for interview and try to solve the exercise problems of the book. 3-6. [5] Describe how to modify any balanced tree data structure such that search, insert, delete, minimum, and ...
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3answers
426 views

What is O(m+n) and O(m*n) in Big O notation? [duplicate]

I understand that O(n) describes an algorithm whose performance will grow linearly and in direct proportion to the size of the input data set. An example of this is a for loop: for n in 0.100 puts ...
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5answers
2k views

Reverse subarray of an array with O(1)

I have an idea how to implement sub array reverse with O(1), not including precalculation such as reading the input. I will have many reverse operations, and I can't use the trivial solution of O(N). ...
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3answers
1k 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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2answers
3k views

What is the simplest and universal algorithm for parsing C++ code? [closed]

I need to do some project specific automatic checking of source codes written in C++ Limitations: Algorithm and its implementation should be simple, easily maintainable, extendable and ...
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2answers
204 views

Gödel's Incompleteness Theorem and Algorithms [closed]

According to Gödel's incompleteness theorem, not every problem can be solved using algorithms. How do we know if a problem can be solved using algorithm? How do we know that NP problems are ...
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3answers
137 views

How to smooth out a diagram? [closed]

we have a data set that creates a graph, it works but the graph has many up and downs and looks really bad, what I like to know if there is a known technique or algorithm or even an API that can ...
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1answer
366 views

Finding all subsets of a set running time

Given a set {1,2,3} output { {}, {1}, {2}, {3}, {1,2}, {1,3}, {2,3}, {1,2,3} } I have only been able to find as fast as O(2^n), is there any techniques for achieving faster results (besides ...
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4answers
155 views

What algorithm would have the fastest average run time and least memory requirements for sorting a deck of playing cards?

Considering a deck of N playing cards with X different rankings and Y different suits (i.e. there are Y cards with X ranking, thus N=X*Y). What is the fastest algorithm to sort them assuming that X, Y,...
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2answers
123 views

Merging Sorted Lists (with no comparison function)

I have a few lists of items (which will likely but not necessarily have common elements). The lists are known to be sorted, but don't have a comparison function (they were manually put into the system ...
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3answers
617 views

Generate unique integer from two integers with algorithm

I am currently trying to come up with an algoritm which would take at least two numbers (say user IDs) and then come up with an unique number which is generated based on these two numbers. Each ...
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2answers
927 views

Common and frequently used algorithms of Data structures? [closed]

I have been programming for a while, and the edge that I am missing over other programming is algorithms. I know what is linked-list and binary tree, but I dont know many more of them. I failed on 2 ...
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2answers
110 views

creating a social trend algorithm [closed]

I want to try to create an algorithm that would rank links according to social trends. I've article links, I've their date of publishing. I also have data from Facebook: comments, shares, likes. My ...
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1answer
117 views

Drawing the Line between Coding Style and Algorithm [closed]

Formatting with Indentations, White spaces, and New Lines obviously fit into the coding style category. if (a == b) { foo(); } // vs if (a == b) { foo(); } On the other hand, something ...
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1answer
137 views

Looking to calculate break even price (minus fees) on an individual level without brute forcing

I am trying to calculate the break-even price on an individual product given a percent of the price I sold it for and the price I bought it for. For example: I buy an item for $200 and the fees on the ...
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2answers
1k views

Accuracy in calculating distance from Android Device using double integral? [closed]

Using TYPE_LINEAR_ACCELERATION suppose I found out that the device is moving at 4 m/s². a(t)=s"(t)=+4 v(t)=∫4tdt s(t)=2/3t³ s(3)=18m How much accurate it would be?
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3answers
142 views

Balanced folder increment

I want to map an integer (let's say 32bits) to a valid path. The integer is an autoincrement value stored in the database. I also don't want at any case any folder to have more than N subfolders. ...
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1answer
103 views

Sorting an array based on another array's order, quickly [closed]

There are two arrays of maps. The first array contains maps of ID values in a specific order (but not necessarily either pure ASC or DESC ordering): // pseudo code first := [ {"id": 1}, {"...
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1answer
235 views

How to selecting Teams with Minimum Difference between Knowledge Levels

For the below challenge from a programming site, I am bit confused. Problem Statement: A Professor of Physics gave projects to the students of his class. The students have to form a team of two for ...
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1answer
779 views

worst case comparisons for special case insertion sort [closed]

Consider an Insertion Sort with a Sentinel on n values, where every value occurs exactly twice in the input (so n must be even). So the best case input for comparisons is when the elements are ...
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1answer
371 views

Unevenly distributed random number generation [duplicate]

Let's say I have to generate random number from 1 to 100, however, the probability of each number is not 1/100, but a predefined probability. How to generate that number? I use Ruby/Python.
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1answer
108 views

Finding “spare time” in a day from within a list of events

I have a list of events which is always sorted chronologically. The start time is always followed by the end time. Times are strings formatted as 'HHmmss'. // list of events var events = [ '...
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1answer
287 views

How to create a some kind of value for sentences? [closed]

I want to identify most matching sentence using some pattern. That means by using java algorithm I want to create identical value for each sentences.Each sentence when entering to that algorithm can ...
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2answers
747 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?
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2answers
320 views

Worth of Algorithm Challenges and event? [closed]

I'm interested in knowing whether it is advisable for computer science students to spend their major chunk of time on the online judges practising programming(like Topcoder and codeforces) or it's ...
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1answer
93 views

How do I implement autocomplete functionality for a big website? [closed]

I am looking to implement a custom autocomplete functionality for a travel website with huge amounts of data. I am thinking of implementing it using a trie. But how do I handle it if the data cannot ...
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2answers
102 views

Permuting and combining the values based on the key

I am trying to generate a table which would show all possible combinations based on the key. To make it more clear lets say I have a kind of Key, Value pair set(Its mentioned kind of because there are ...
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1answer
412 views

How to implement a genetic algorithm with distance, time, and cost [closed]

I want to make a solution to find the optimum route of school visit. For example, I want to visit 5 schools (A, B, C, D, E) in my city. Given the choice of five routes regarding what school I should ...
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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 ...
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2answers
99 views

Figuring a max repetitive sub-tree in an object tree

I am trying to solve a problem of finding a max repetitive sub-tree in an object tree. By the object tree I mean a tree where each leaf and node has a name. Each leaf has a type and a value of that ...
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1answer
536 views

Grid walking explanation [closed]

There's a problem on hackerrank.com called Grid Walking. Here is its description: You are situated in an N dimensional grid at position (x1,x2,...,xN). The dimensions of the grid are (D1,D2,......
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1answer
123 views

Pathfinding in a 3d world with obstacles?

What are some methods for pathfinding in a 3d world? Object X needs to move from Point A to Point B but it might have to avoid things like asteroids, planets or gas pockets that makes the object ...
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1answer
111 views

Algorithm to 'segment' a number into blocks of n?

I'm not sure how to word the title properly, but the problem goes something like this: I have 5 nodes, and node 0 is the "master". User inputs a number, e.g. 100 to the master. master "splits" the ...
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1answer
221 views

How to solve linear recurrences involving two functions?

Actually I came across a question in Dynamic Programming where we need to find the number of ways to tile a 2 X N area with tiles of given dimensions.. Here is the problem statement Now after a bit ...
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1answer
526 views

Does implementing algorithms improve your programming skills? [duplicate]

I have been self studying algorithms and data structures for some time now and currently enjoying it. Whenever I understand an algorithm, I usually try to code them from scratch for fun and I always ...
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1answer
353 views

Optimal movie schedule

Let's say Mr. A goes to cinema and he gets a movie schedule. There are N movies on the program today (1 < N < 50) and for every movie the time of the start and the time of the end are given in ...
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2answers
89 views

Store a tree with near next neighbours

I would to find an efficient structure (speed and volume) to store nodes and their neighbourhood. My input is build out of stings in the following format ./X/Y.log where X ∈ [0,359] and Y &...
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0answers
24 views

Implementation of qsort [on hold]

I have been looking for implementation for qsort but using google I find implementation for something like this void qsort(int[] arr, int left, int right); What I want is implementation for ...
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0answers
70 views

Formalising algorithms - Greek symbol uses/sources

I am looking to formalise an algorithm that I have created, however, I am having trouble knowing when to correctly use Greek symbols (such as Epsilon, Omega etc.). Are there any guides/standardised ...
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0answers
49 views

Sorting a 2d array in java [on hold]

I'm a high school student who is interested in computer science, I asked this question to my teacher but she told me not to bother messing around with code and trying to understand how to modify ...
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0answers
34 views

Best way to find longest common subsequence by hand without computer

I know how to solve the Longest common subsequence using a computer, but how would one do it without the use of one? I also know that I can use tables for help, but what if I get two strings of length ...
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0answers
46 views

Algorithm for Multiple Choice Test Prep App

I'm working on app that helps students prepare for a specific exam. I have a database of 1000 questions, question categories, multiple choice options, hints and correct answers. Today, the app simply ...
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2answers
56 views

Find best layout to reduce use of space or material

Example case: You have a truck, that can hold 2.8m by 3.2m by 16m of storage capacity. You you get a bunch of physical objects you want to store in that truck. These objects are not always cubic, but ...
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2answers
222 views

Programming judge with versus system [closed]

I'm looking for a programming judge system which supports putting contestants programs against each other in "matches". The format could be either for example a tournament style or chess ranking, but ...
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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 ...