# Tagged Questions

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.

5 views

### about Max MSP program, how can I do a list of one columns data that has 2 columns

I am using the Max MSP programming language, Windows 10. In my patcher file I have two columns: data value and its size frequency. I like to sort the data value according to the appropriate size ...
33 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 ...
19 views

### Given a set of N coordinates, how can I determine which of them are closer to each other? [on hold]

I would like to know what's the best way to solve the following problem; Given a set coordinates: coords = [ [ 6.200992, -75.578738 ], [ 6.174297, -75.348264 ], [ 6.199156, -75.573768 ], [ ...
453 views

### Can I use a patented algorithm? [closed]

Similar to this question, but for a very different situation. I've been working-up some example code to accompany a proposed programming challenge and asking questions about the difficult bits. In my ...
150 views
+50

### 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 ...
219 views

### Min weight feedback edge set with DFS?

Exercise from The Algorithm Design Manual 6-10. [4] Let G = (V,E) be an undirected graph. A set F ⊆ E of edges is called a feedback-edge set if every cycle of G has at least one edge in F. ...
86 views

### How do I mutate a value in a genetic algorithm using Gaussian distribution?

I've been reading 'Introduction to Evolutionary Algorithms'. This method is stated, but not described, and I can't find anything more specific online. p44/45 of 2nd Ed for reference. adding to the ...
771 views

### Is a genetic algorithm a correct approach to this problem?

I am trying to calculate a set of items that produce the highest damage output in a video game. There are about 50 different items, of which you can choose 6. There are all sorts of conditions that ...
158 views

### Sorting a large number of unknown items with multiple stacks

Here is a problem I'm trying to solve for a personal project. I'm not exactly sure how best to even approach it. Problem: I have a single stack already populated with several thousands of unknown ...
82 views

### How to compress and send 36,864,000 numbers per second over a network? [on hold]

You have a 3D mesh made up of 307,200 vertices. Or to put it in programming terms, you have an array with 307,200 entries whereas each entry is an object containing the properties id, x, y and z, each ...
77 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 ...
147 views

### Non-fixed-size Fenwick Tree implementation

I'm planning to implement a non-fixed-size Fenwick tree. That is, a Fenwick tree that allows interleaving range queries with adding/removing elements. All implementations and samples I've seen so far ...
107 views

### Split multiple overlapping intervals to non overlapping intervals

currently I try to build an algorithm to split an array of overlapping intervals to a new array with non overlapping intervals. For example: Array of overlapping intervals: [ {0,7}, {8,12}, ...
49 views

### Paxos consistency [migrated]

I'm looking at the paxos family of protocols for solving consensus in a network of unreliable processors. I'm working through scenarios where processors fail, and I know I'm wrong, but I don't know ...
102 views

### How to triangulate a 3D polygon? [closed]

How can I create a set of triangles to fill a 3D polygon? The polygon is an ordered sequence of 3D vertices defining a single geometric contour (a closed path). Vertices are not necessarly coplanar. ...
56 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. ...
53 views

### Backpropagation in layman terms [closed]

I've been studying neural networks, and I'm beginning to understand the basics. I know what the backpropagation algorithm does. It feeds sample input and calculates an error against a given output. ...
323 views

### Efficient algorithm for Virtual Machine(VM) Consolidation in Cloud

PROBLEM: We have N physical machines(PMs) each with ram Ri, cpu Ci and a set of currently scheduled VMs each with ram requirement ri and ci respectively Moving(Migrating) any VM from one PM to ...
19k views

### Determining if an Algorithm is O (log n)

I'm refreshing my CS Theory, and I want to know how to identify that an algorithm O (log n) complexity. Specifically, is there an easy way to identify it? I know with O(n), you usually have a single ...
518 views

### Computer vision algorithms (how is this possible?)

I recently stumbled across a company that has created what appears to be a computer vision technology that is capable of detecting shoplifting automatically and alert its users. LINK Watching some ...
22 views

### Why does this code take up so much memory? [migrated]

I created a solution to this problem on leetcode: All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes ...
126 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, ...
117 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 ...
151 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 ...
171 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 ...
285 views

### Fast indexing of k-combinations

I'm revisiting an old problem that I was working on some time ago. A typical scenario is "3 bits are set within an 8 bit integer", i.e. 00000111. All unique combinations with 3 set bits can easily ...
101 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 ...
28 views

### How to split these products to packages? [migrated]

I have this group of products: Product Quantity Weight Per Unit pro#1 7 5kg pro#2 5 5kg I want to split these products into packages, but the ...
1k 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 ...
116 views

### Measure and locate areas of similar value in an image

I saw this picture online and wanted to see if I could create an algorithm to give ordinary images an effect like this: http://justinlivi.net/wp-content/uploads/2011/01/Living_In_Digital.jpg My idea ...
111 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 ...
91 views

### Best-matching comparative values using all items in array

I have two arrays of objects (items) in the exact same format. Each item represents a wager, and each array represents one of two outcomes for that wager (ex: Team A vs Team B). Both arrays look ...
75 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 ...
128 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 ...
133 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 ...
445 views

### How to extract the active code path from a complex algorithm

I have been puzzled lately by an intruiging idea. I wonder if there is a (known) method to extract the executed source code from a large complex algorithm. I will try to elaborate this question: ...
60 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 ...
134 views

### Image segmentation - show or hide clusters

I'm trying to make a small program in c#, that will downsample image to specified amount of colors (using K-means). Then, user will be able to hide\show colored areas(clusters) in image. I've ...
43 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 ...
203 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? ...
124 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 ...
203 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 ...
1k views

### Is it possible to efficiently store all possible phone numbers in memory?

Given the standard North American phone number format: (Area Code) Exchange - Subscriber, the set of possible numbers is about 6 billion. However, efficiently breaking down the nodes into the sections ...
71 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 ...
244 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 ...
146 views

### Finding the closest n points to any arbitrary point in two dimensions (r-tree, quadtree, spatial index)

I have a distribution of two dimensional point objects. How is it possible to find the nearest N number of points to any given point without iterating over the entire collection of points (and only ...
92 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 ...
609 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 ...