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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Syncing different nosql datasources efficiently

I have two dbs I am dealing with right now - Elasticsearch and Mongodb. Mongodb is legacy in the application in that I am not happy for its presence but it is there and in use, I am interested in ...
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2answers
124 views

Big O of 2 interesting Algorithmic functions [closed]

This is my homework(I have attempted it, and there are no references for questions like these) Determine whether or not these functions are polynomial run time and determine the constant c for ...
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403 views

Which weak algorithmic strategies I have that lead me to failing coding this simple algorithm? [closed]

I am a graduate student in computer science who graduated recently from a famous university. I applied to my first software engineering job and I failed the technical interview by failing to answer ...
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1answer
124 views

Algorithm to find the closest summation of elements in a list to a given number [duplicate]

Say I have a list {1,3,7,2,11,8,2} and I want to take x elements from the list and get the value 15.5. Is there an algorithm that would give me x elements in a list that, when added together, get ...
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1answer
85 views

find the minimum number of sets

Let's explain my question with example I have some integer sets for example S1 = {2,3} S2 = {2, 5} S3 = {4, 5} S4 = {4} S5 = {5} And I have sample set Ssample with 4 elements {2, 3, 4, 5}. So ...
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794 views

run time of nested while loop inside for loop

I'm here to clarify my understanding of the run times of these 2 algorithms: Algorithm1(n): For i = 1 to n j = 1 while i+j < n j = j+1 and Algorithm2(n): For i = 1 to n j = ...
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3answers
3k views

Efficient algorithm to count number of substrings divisible by 3

Given a string of decimal digits, I have to find the number of all substrings divisible by 3 in the range L to R [both inclusive], where L & R are index[1-based] of the specified string string ...
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1answer
79 views

What is the minimum cost graph inside a strongly connected component, which connects every vertex?

So for MST there are 2 possible definitions in an undirected graph. Keep in mind that in an undirected graph the MST algorithm always has n - 1 edges and no cycles. In an undirected graph, it doesn't ...
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3answers
187 views

Is there an algorithm to determine the amount of work needed to keep workers busy?

I wrote a multi-threaded program that randomly generates strings, and after generating, checks to see if the string contains a certain value. Namely, StringGenerator and StringChecker. What I'm trying ...
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4answers
271 views

Range of values based on key values

I'm trying to implement a method of searching trough a large amount of 2D points for those that match a certain range. I'm thinking of creating HashMaps for <X, Point> and <Y, Point> but ...
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1answer
242 views

Solving a Sudoku variant with an unknown element

I recently stumbled upon a special Sudoku variant and am now struggling to effectively solve it programatically. Consider the following initial 6x6 grid: The rules The red question mark is ...
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1answer
65 views

Creating a tree of objects based on the commonness of its properties?

I have an algorithm problem. I'll simplify the issue, because most of what I'm dealing with has nothing to do with the algorithm I need. Basically, I have a list of objects that each have properties. ...
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73 views

Global relabeling heuristic: Push-relabel maxflow

I have a correct, working implementation of the preflow-push-relabel maxflow algorithm [2]. I am trying to implement the global relabeling update heuristic [3], but have run into some issues. I have ...
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2answers
3k views

Algorithm to merge two sorted arrays with minimum number of comparisons

Given are two sorted arrays a, b of type T with size n and m. I am looking for an algorithm that merges the two arrays into a new array (of maximum size n+m). If you have a cheap comparison ...
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0answers
123 views

Design an algorithm with network flow

Given a matrix A with 0 and 1 entries. Neighbours of a[i,j] are a[i-1,j], a[i+1,j], a[i,j-1] and a[i,j+1] (if exists any). Tow neigbour entries are an Improper pair if they have not equal values. if ...
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1answer
182 views

Hash function with uniqueness guarantees and controllable entropy

Is there a class of hash functions that meets the following specs: Upper and lower bound can be specified Uniqueness is guaranteed as long as the input is between the upper and lower bounds Amount ...
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1answer
137 views

Silverlight-based “area of influence” algorithm

I am in the process of developing a tool for a game called MechWarrior: Online which defines a map of an area of space called the Inner Sphere. Essentially, this map is a set of points (planets) on a ...
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1answer
218 views

Shortest path to visit all nodes [duplicate]

I am given a set of tourist attractions(nodes identified by x, y) and i need to find the shortest path to visit them. The way i thought of it, is i will ignore if there are streets available and ...
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120 views

Algorithm for sweeping a 2d shape along a curve?

I am trying to create a graphics application where the user can use an arbitrary shape as a "brush", which will be swept along the drawing path. The shape may be transformed along the path (rotated, ...
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3answers
156 views

How to code a one-sided virtual economy

I'm attempting to make an online game with a mini-economy in it. The challenge is that the only person selling anything will be the website itself, and hence the supply and demand curve doesn't apply ...
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1answer
73 views

Algorithm to find the fewest number of values (from a set of values) where the sum equals a value (+ one more condition)

The simplest way to explain this is with an example. You're given then number 19 and you have a set of numbers to choose from: 1, 2, 3, 4, 6 When choosing values from the list (which can be ...
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3answers
198 views

Concept for dealing with recurring appointments

Our company implemented a calendar system a few months back with recurring appointments, using iCal strings to store the recurring appointment criteria. We are starting to run into performance ...
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7answers
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Is there any algorithm pattern to protect any content in the web to ensure I am the first one who created it?

A few years ago there was this hacker (don't remember who he was) that full disclosed a vulnerability in a given system, but to make sure nobody took credit for that, he created some kind of PGP key. ...
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1answer
95 views

Merge directed acyclic graphs minimizing number of nodes

I have some DAGs (directed acylic graphs) and I want to merge them in order to minimize the number of nodes (we could say that every node has a cost, while edges are free). These four different DAGs ...
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1answer
100 views

Permutting a list of numbers in order to get a list which satisfies given condition

Here is algorithmic problem I'm trying to solve: Given a list [x_1,x_2,...,x_n] return a permutation of elements of the list [y_1,y_2,...,y_n] (where for each i we have y_i = x_j for only one j) ...
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2answers
121 views

Porting an algorithm implementation licensed under GNU GPL v3

I'm working on a JavaScript port of a red-black tree implementation in Java from the book Algorithms 4th Edition, by Sedgewick and Wayne. I believe that my JavaScript port qualifies as a derivative ...
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1answer
177 views

Matching algorithms in context of data quality problems

I work for an organization that has lots of databases containing person information. The data quality is poor. One case was a surname I found like this (this is the worst-case scenario): Mark ...
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1answer
119 views

Matrices calculations on partial shape matching

I'm working in a shape recognition project where it is supposed for me to develop an application that receives two images: an original one and a sketch made by a user. I am supposed to detect contours ...
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2answers
104 views

Track a series of choices with a single number

I want to track a series of scored questions in a single number (the total score). Is that possible? and how? For example, I have 30 questions with either 3 or 2 choices. For any given question, the ...
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1answer
95 views

Finding same numbers in a matrix

I have a question here and I am trying to find a solution of it. But I want to see some other opinions as well. The problem is the following: There is a matrix NxN which holds integer numbers. ...
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1answer
131 views

Generate algorithm to solve peg solitaire

I know that with regression it is possible to generate a mathematical function based on experimental data. I was wondering, maybe there is a way to generate something more complex. I have a single ...
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1answer
101 views

How do I efficiently send notifications for different events to different users based on their preferences?

I'm creating a notification system for particular events. A user can set the criteria that match particular events (ie. New item, changed item, closed item etc) Items have different characteristics ...
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2answers
155 views

On-the-fly, random partition of a range of numbers [0,N] in groups of max M size

Suppose that you have a range of numbers from 0 to N that you want to randomly separate in groups of max M sequential numbers. This is easily done with a bitmap and a random number generator, but it ...
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3answers
131 views

Algorithm Analysis: In practice, do coefficients of higher order terms matter?

Consider an^2 + bn + c. I understand that for large n, bn and c become insignificant. I also understand that for large n, the differences between 2n^2 and n^2 are pretty insignificant compared to the ...
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128 views

Algorithm for sport tournament bracket tree

I would like to develop a library that: receive n players in input response with the tournaments brackets in output. I would ask you what kind of algorithm I have to use to choose the correct tree ...
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1answer
144 views

What algorithm-family or problem-space description fits? Industrial process feeding ingredients to process

Our process continuously feeds (normally <= 8) ingredients from a choice of hundreds, using 3 feeders only. So if ingredient count X is > 3, 3 through X are stirred together in a batch process and ...
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90 views

In a mutual credit network, how would you program an automatic jubilee?

A little explanation might be needed. I mean mutual credit the way that it's defined here: a type of alternative currency in which the currency used in a transaction can be created at the time of ...
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2answers
591 views

Most Efficient way to Compute the sum of divisors of N (1 ≤ N ≤ 1 000 000 000)

I want to write a code which computes the sum of divisors of a number N(1 ≤ N ≤ 1 000 000 000), excluding the number itself. However, I need an efficient way to do it. It suppose to print the answer ...
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1answer
165 views

moving around virtual keyboard

I'm creating virtual keyboard using javascript/html/css. And I can't find a good algorithm for moving from one button to another in different directions (top-bottom, left-right). Lets say I ...
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1answer
169 views

Is this still a Greedy Algorithm

As a preface I will state this is for a homework assignment. I have already discussed this with the professor and will not be using this design. This purpose of this question is whether or not the ...
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2answers
242 views

Why Do B+ Trees Have a Minimum Occupancy of 50%?

As far as I can tell, the basic operations (add, delete, search) on a B+ Tree would function the same if minimum occupancy was 1, or 1/3, or any other function on node size. All the sources available ...
2
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2answers
177 views

Finding shortest path between nodes with a twist

Note: if you feel that I should include code, please tell me. I am solving a problem of finding shortest path between nodes. I am given the vertices between nodes, however they are one sided (ie you ...
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1answer
128 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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8answers
6k views

Function guaranteed to never return the same value twice [closed]

This is a question I was asked at a job interview, and I can't figure out the answer they were looking for, so I'm hoping someone here might have some ideas. The goal is to write a function that is ...
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1answer
62 views

Simulated Annealing Contradiction?

The entire idea of simulated annealing is to avoid getting stuck in local optimums, which is why sometimes, a worse solution is accepted. However, simulated annealing will automatically accept a ...
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1answer
547 views

Why does this evaluation function work in a connect four game in java

I am exploring how a Minimax algorithm can be used in a connect four game. I was looking through a program and found this evaluation function. private static int[][] evaluationTable = {{3, 4, 5, 7, ...
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111 views

Rideshare algorithm to be used for scheduled and adhoc journeys

I need some help writing some pseudo code for a rideshare system for taxi drivers. The idea behind it is that it would combine real-time incoming taxi journeys and pre-bookings in real-time. The ...
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1answer
136 views

What is the justification for the running time of this loop?

I don't understand why the running time of the following loop is n+2 ? Also why the running time of the statements inside the loop is n+1 ? Double test(int n){ int sum=0; -> 1 time ...
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4answers
297 views

Mark x% items in stream

There are n items (n is known and > 1,000,000,000). I want to randomly 'mark' x% of n-items in stream. (n and x are known) Items are in stream ,one directional (you can't go back) processed item ...
2
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1answer
90 views

Finding the fewest sets which contain all items

I am wondering if there is a known algorithm for solving the following. Data: There is a number of sets containing items. An item can be a member of more than one set. Aim: return the minimum number ...