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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3
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2answers
196 views

How to find the closest right neighbour in a tree?

Given a class: public class Node { public List nodes[]; public Node right; //NULL for now } What's the best way to fill the "right" element of all tree nodes? N ...
5
votes
6answers
427 views

Algorithm for determining transactions among weekly data series?

I'm trying to develop a small reporting tool (with sqlite backend). I can best describe this tool as a "transaction" ledger. What I'm trying to do is keep track of "transactions" from weekly data ...
4
votes
1answer
179 views

Detecting surface faces of a huge 3D mesh/grid

I've written a module in my application that creates a mesh from existing coordinate and face data. The number of vertices in the mesh could easily exceed 10 million and the same goes for the faces. ...
-3
votes
1answer
173 views

Any Deterministic Compression Algorithms out There? [closed]

The title says it all, basically. Are there any deterministic compression algorithms - that is, an algorithm which, given identical input, will always produce identical output? As far as I know, ...
-1
votes
1answer
133 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 ...
0
votes
1answer
276 views

How does Luhn algorithm relate to cryptograpic hash functions?

What I am interested is the similarities and differences between the two. It is my understanding to present time that Luhn algorithm is a type of checksum function same as some cryptographic hash ...
4
votes
2answers
84 views

How do you avoid dominant solutions in multi-objective simulated annealing?

Imagine an RPG game were you can cary N items, and you want to maximise your damage, attack speed and armour, given a set of items. I implemented simulated annealing where a permutation simply ...
2
votes
1answer
462 views

Grouping algorithm

We've developed an algorithm that depending on the check-in time of some workers and their living place, calculates the way to group them into some vehicles and the route which must be followed by the ...
21
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4answers
2k views

Calendar/Planning algorithm

I'm facing a problem I'm not sure how to approach. I have to generate a calendar for employees, each of them having specific work constraints (some personal, some common) What I'm working with : I ...
-1
votes
3answers
132 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 ...
3
votes
3answers
142 views

Determine frequency-range that matches closest to input list of frequencies

Since this question is not about "code not working", I'm asking my first question here instead of StackOverflow. Inform me if any required information is missing from the question. Setup: I ...
0
votes
3answers
283 views

Analysis of insertion sort does not equal O(n^2)?

I'm learning more about algorithms and data structures. According to Wikipedia and other reliable sources, an insertion sort has a worst-case time complexity of O(n2). I'm attempting to measure that ...
2
votes
1answer
158 views

Figuring out the mean of a stream of data, disregarding values that are way off bounds

I have a stream of integer data and want to perform some statistical analysis on it. I want to calculate the mean and the standard deviation of it. So far it isn't hard, but keep in mind that I am ...
0
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0answers
182 views

Finding meeting point of Slow and Fast pointers in Linked List Loop

I am aware that the solution for finding a loop using Hare-Tortoise approach works. I have a working code that is able to detect loops in a Linked List. My question is on how to find the meeting point ...
0
votes
2answers
95 views

Is there an algorithm to avoid getting in hundreds of datapoints from API to represent a bar graph?

I am showing a graph on HTML5 canvas using the flot charting library for a between a start date and an end date. It's fine as long as the period is less than a year or so but if the user selects a big ...
1
vote
2answers
236 views

Shuffle/Randomize a collection without knowing the number of items? [closed]

Let's say I have a sequence of items of unknown length, n. I want to randomize the order of this sequence without having to go through the entire sequence. Are there any algorithms that can do this? ...
1
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0answers
96 views

Search algorithm on sequential data model

For sequential data models like LinkedList, search algorithms like linear-search and binary-search are well known. Are their any other search algorithms apart from these two, that work on sequential ...
2
votes
1answer
222 views

Is there a better algorithm to distribute integer to X integers minimizing their difference?

Is there a better algorithm to distribute values from one source to X destinations minimizing their difference? I have some source integer. I need to know how much of that value I need to distribute ...
2
votes
2answers
154 views

Incorporating functions into a Shunting-Yard algorithm implementation

tl;dr What would be a simple way of incorporating functions into a Shunting-Yard algorithm implementation? If only expressions like function(arg1, arg2, arg3) were allowed (where function is some ...
18
votes
5answers
830 views

Algorithm for calculating a bullet path to a target with max. 2 ricochets

Sorry for the poor title but I didn't have a better way to phrase it... So there's this amazing game by Nintendo (yes!) on Wii called WiiPlay. There're 9 minigames in it, and my favorite one is ...
2
votes
2answers
144 views

Algorithm to go from infix notation to a tree

I've been trying to figure out an algorithm to go from an infix equation to a syntax tree, like so: (1+3)*4+5 + * 5 + 4 1 3 However, I don't just want it to handle operators, I ...
0
votes
0answers
111 views

Calculating audio delay to eliminate echo in VoIP

In this issue, the microphone at point A records audio, compresses it, and sends it to the server at point B somewhere "in the cloud." The point B server then figures out what rooms the recorded ...
9
votes
3answers
2k views

My algorithm that extracts the largest box that can be made from smaller boxes, is too slow

Imagine a cube based world (such as Minecraft, Trove, or Cube World) where everything is made up of identically sized cubes and all the cubes are of the same kind. The goal is to represent the world ...
0
votes
1answer
135 views

Bad idea to use the same test cases for multiple parts of a contiguous algorithm?

I'm working on an algorithm that's split up into multiple parts, each of which performs different tasks but is more or less separate from the others, by which I mean the only interaction between the ...
1
vote
2answers
118 views

Multi-pattern matching

I have a given byte array in C and I need to match it against several byte arrays and return true if there is any match. I can make various memcmp's but I feel that it is very inefficient. Do you ...
1
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2answers
681 views

Is the time complexity of a while loop with three pointers different than 3 nested for loops?

This program (written in ruby) finds the largest 3 numbers in an array (without sorting the array). It has a while loop with three pointers. My fist instinct, since there is only one loop is to say ...
19
votes
4answers
3k views

When speaking, how can I say that the time complexity order of an algorithm is O(N log N)?

What term can I use to describe something with O(N log N) complexity? For example: O(1): Constant O(log N): Logarithmic O(N): Linear O(N log N): ?????? O(N2): Quadratic O(N3): Cubic
2
votes
1answer
460 views

Precedence of function in Shunting-yard algorithm

I am working through the Shunting-yard algorithm, as described by wikipedia. The description of the algorithm when dealing with operators is as follows: If the token is an operator, o1, then: ...
0
votes
0answers
70 views

clustering of strings with variable-length prefixes

I've got bunch of strings with variable-length prefixes (or postfixes - I can always revert them) as follows: 0155555555 523455555555 755555555 ... 87129999999999999 119999999999999 09119999999999999 ...
2
votes
1answer
67 views

Looking for an Appropriate Search Algorithm

I am currently planning an upcoming project and am looking for an algorithm for searching a database. The search is as follows; There will be some specifically labelled criteria (or fields) and I ...
1
vote
1answer
296 views

How to generate Generate Hash incorporating time stamp so it can be unhashed to get the timestamp when it was generated?

I want to create hash based on random id, That hash has to be valid for only 15 minutes. Is there a way to do that? I'm using this for form submission. If some unknown submitted form or some one ...
3
votes
1answer
219 views

Finding the optimal root

I am trying to solve a quora hackathon challenge question. The question descrpition is as follows : For the purposes of this problem, suppose Quora has N questions, and question i (1≤i≤N) takes ...
3
votes
0answers
363 views

Fast fixed-size (256 bit) integer modulo/division

What is the fastest way to divide two 256-bit integers? They are represented as an array of 26-bit words, each stored in 32-bit integers. I have access to a 64-bit type if that's useful. It seems ...
2
votes
2answers
111 views

Why use a unique hashkey for form submissions?

I have multiple forms and use AJAX to submit them. I asked my boss if he needed any specific format for the form ID and he told me to generate a unique hash and keep it in session; check it whenever ...
-3
votes
2answers
162 views

Integer Map Algorithm [closed]

For my project, I need to map integers so that inputting int X will output int Y where both X and Y are defined during runtime. I've used Dictionary<int,int> in .NET but its memory use is too ...
0
votes
1answer
244 views

How to sort fractions (small numbers)

We have 100 000 fractions: Let's consider following fractions. p/(2^q) such that 0 <= p,q <= 10 As you can see there are <= 10 * 10 different fractions, but we have 100 000 that we have to ...
1
vote
1answer
176 views

Algorithm to cut out and straighten rectangles from image

I am looking to write an algorithm to cut rectangular images and straighten them in a new image. The bigger concept is that I will be scanning a bunch of physical pictures (on a physical scanner). ...
0
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2answers
112 views

AABB collision algorithm with a condition

So I'm doing a 3D implementation of collision detection. Considering Boxes are oriented on the axis. They are rotatable but has to be orientated on the axis. Box A and Box B cannot go through each ...
2
votes
1answer
82 views

Seeds distribution algorithm with complexity better than O(n^3)?

I have included my approach and solution. My solution works fine, however, is unoptimized with O(n^3) complexity An NGO is running seed distribution program. It has limited quantity of varied quality ...
2
votes
2answers
184 views

Algorithm to solve this “treefarm” puzzle

How would I go about writing a program to solve this kind of puzzle: The green squares represent trees, and you have to plant them in such a way, so that: Trees do not touch each other at all (not ...
3
votes
2answers
202 views

Obstacle bypass in 2d environment

For this 2d grid (black square are not penetrable, white square are): I want to find path who permit to move an object to a start point (x:18, y:18) to a end point (x:1, y:1), square by square. ...
4
votes
3answers
340 views

Work out which parcel deliveries we ship ourselves and which we outsource

Firstly, I hope I'm asking this in the right place. I work for a large online retailer in UK. We ship approaching 2000 orders each day and are growing very quickly. We currently use multiple delivery ...
6
votes
5answers
296 views

Hamming Distance using a dictionary

First time poster. I'm currently programming a hamming distance program using a dictionary. So if we start with the word "cat" and we want to transform it into "dog", the sequence is ...
0
votes
0answers
52 views

Final array after M updates on Segment Tree

I am stuck in a middle of a problem. I have made segment Tree of N elements and performed M updates through lazy propagation Now I need to store the final array (to some array B of size N) after all ...
1
vote
1answer
266 views

What does it mean for an algorithm to converge?

I keep coming across this term when reading about reinforcement learning, for example in this sentence: If the problem is modelled with care, some Reinforcement Learning algorithms can converge to ...
2
votes
1answer
61 views

Which algorithm to find the shortest (nodes count) path that encompasses all polygons inside a larger polygon?

Inside a large polygon (say the USA boundaries) I need to find the shortest path that will encompass smaller polygons (say the following cities: Kansas city, St Louis, Memphis, Oklahoma City) By ...
4
votes
1answer
123 views

Improve bisection method or alternate algorithm for efficient determination of text font size to fit in a box

I need to find the font size of a text that fits in a box. Given my current font size, I can get the bounding rectangle of the text. If I set some arbitrary min and max font size, I suppose I can ...
1
vote
0answers
132 views

Software Design, Generic Programming, Physical Devices, and Algorithms in C++ [closed]

I often have data that in some contexts I want to handle uniformly, but in other contexts I wish to differentiate it. For example, I could have a vector that is series of angles or a series of ...
0
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0answers
45 views

Approaches to combinatorial optimization problem

Problem I have the following combinatorial optimization problem: A set of applications need to be distributed among a set of nodes. Each node has a capacity and each application has a required ...
0
votes
0answers
67 views

Simple Path to Route Algorithm

I'm currently conducting research into subway paths, but stand in front of a problem, with no programming knowledge and an extremely short time-limit. Probably the question I am asking is trivial, ...