# Questions tagged [algorithms]

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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### A collision-free hash-like function for use in hash tables and other data structures?

A short introduction to the problem: I'm working with a small database where I have a table of strings (web URLs, to be precise) as pairs: hash|string. Another table references these strings by hash ...
83 views

### How to resolve multiple user serve on multiple location appointment booking system

I'm trying to build an appointment system but at one point I stuck Problem: I define available slots for the next 7 days with help of a cron. I have multiple users serve service more than one ...
242 views

### Cumulative sum of overlapping increase/decrease over time

I am looking for an efficient way to handle a calculation. I have lots of timestamped events, representing loading and unloading of trucks. I need to construct the filling rate of these trucks over ...
41 views

### Matching closest position of a sequence from another

I have 2 sequences: One is a videoclip with the image taken by a drone's camera The other is a file with a list of chronological data from the sensors Example: time 0: speed_x=1, latitude=0.001, ...
148 views

### Subdomain matching

I am working on a small plugin for a DNS server. I have a static list of domain (sometimes subdomains too) names: gaming.xyz.com facebook.com mail.example.com blog.example.com I want to check if a ...
949 views

### How to find matching profiles?

I'm developing backend for a dating app, in which each user has a profile of his/her characteristics a profile of ideal match's characteristics There are dozens of characteristics like gender, ...
646 views

### Is it better to write an efficient algorithm or code that is easier to understand?

So I was recently given a coding assignment from a large financial firm, and I thought of two ways to solve the problem. One of the ways involved 1 outer for loop and 1 inner for loop. In this case, ...
425 views

### Chess: Efficiently deciding whether a check mate has been made

This question addresses building a Chess engine. I've done just that, and in my humble opinion quite elegantly. But I'm missing my ending conditions. Here are some pseudopython functions that I use. ...
61 views

### Hashing tag list to perform faster search

I have a list of items. Each item have various properties. Each item can be tagged, like tagging a post here. Right now, tags are represented using a Tags property, that is a string and it looks like ...
39 views

### Flowcharting 2 methods that use the same variable

so I need to flowchart something similar to the picture. The the first flowchart on left and the 2 flowcharts on the right is on different classes. The someClass have a instance variable named MyVar ...
247 views

### Is the Factory pattern good for this situation?

Im developping for my company a software where clients can requests app deployements and upgrades. Each request has 3 status (Validated, Started and closed). For every type of request (deployment ...
1k views

### Algorithm to sort ten million 7-digit integers in ascending order with just 1.5Mb RAM?

Given a file containing at most ten million 7-digit integers with no duplicates. What is an efficient way to print these numbers in ascending order using just 1.5MB RAM and reading the data just ...
375 views

### How fuzzy search is implemented for file paths

Say I have file paths like this: my/long/directory/structure/index.js my/long/directory/structure2/index.js my/long/directory/structure3/index.js my/long/directory/structure.../index.js my/long/...
167 views

### When implementing new features that are similar to other features, do you make the older features more generic?

This may come off as a bit confusing, but it's a question that I keep finding myself asking as I pile on more and more responsibility to older systems and features that I designed previously. Trying ...
150 views

### phonetic algorithms for words that aren't surnames?

I've been doing a little research into algorithms for matching spelling mistakes in names. From Soundex through to metaphone and Beider-Morse. All of these algorithms generally focus on last names ...
68 views

### Decision tree for storing subscription info

I have a system in which user creates an entity. Now this entity has attributes which are dependent on many external systems. We have all those pipelines in backend which updates these entities when ...
680 views

### Find the min/max length of directed graph

The problem is simple on paper... but a bit harder when it comes to write the algorithm to solve it. Let's use the following graph: First part This graph has an entry point A and two possible exits ...
165 views

### Executing an algorithm constantly on slow and fast machine

Is it possible to create an algorithm that will execute at the same rate and speed on faster and slow computers. What i mean is, i have a year 2000 desktop that can run a certain computational ...
193 views

### What is the best algorithm for implementing a system with a complex execution path?

I am currently working on an implementation that based on a set of user configurations should output a final decision. The multiple configurations are evaluated several times at different stages of ...
146 views

### Find a string in list of strings

Background: I am writing an application for a small embedded device. There is a static list of strings: currently about 500 strings and string length is 12 characters on average. The list might ...
84 views

### Simulating Comparison Without Using Comparison Primitives

In the same way that you can simulate the if statement and functions, I am wondering if there is a way to simulate the comparison operators ==, !=, >, >=, <, <=. For example, in ...
123 views

### How can an iterative algorithm be controlled dynamically?

Suppose we need an iterative algorithm for mathematical optimisation. Each iteration takes a long and random time. After each iteration, a stopping condition is checked for the iterate x, based on ...
2k views

### Shuffle in music players

I always hear how it is hard to implement shuffle algorithms for music players, but never really the explanation for it. What makes it hard? Take for example how I would implement one: First the ...
644 views

### how can i return the median of a threaded binary search tree in constant time?

I'm having a trouble with understanding how to implement and find the median of a threaded binary search tree in constant time. The tree consists of a worker's id and name. The given details are ...
98 views

### Find nth best path in graph G from node A to node B (without loops)

I'm making an graph layout optimizer and need to find paths from node a to node b in graph g. It has gone pretty well so far, but I lack an algorithm to take the next step. So far I've used BFS to ...
285 views

### Algorithm to generate all the possible combinations

I develop an application using WinForms/C#. In my software I have a List of objects, let's say List<Item> Items. There is also another List of objects, let's say List<Factor> Factors. ...
330 views

### Data Structure for “Intuitive” Text Matching

I've noticed that text editors and such have a more-than-prefix/suffix-based pattern matching algorithm going on behind the scenes. And StackOverflow's tag matching algorithm does more than just ...
31 views

### Sorting a list of objects with re-ordering and different views

The problem I have is this: I have a list of items. Each item has multiple properties. I have a view where I display all items and I have a view where I display the items based on values in properties....
761 views

### How to reason about complexity of Merging k sorted linked lists?

I am trying to understand Big O notation better to be able to reason about it in a much clearer way and therefore, need some feedback on my analysis given below for problem: Merge k-sorted linked ...
91 views

### System design for credit calculation usage

We are implementing a system where a user can purchase 'credits' to be spent on two items. I am hoping for suggestions on how to implement such a system. We have two ways of spending credits: ItemA ...
120 views

### Improving my inelegant Haskell deduplication function

I'm working on learning Haskell, and one of the simple exercises I put myself through to this end is writing a function that deduplicates a list, removing all of the duplicate elements of a list such ...
107 views

### Array rotation algorithm

I'm developing an application which sends quotes to clients via email. Since quotes are obtained from various resources (per each client) they end up in a single array which is then used as a source ...
272 views

### Algorithm: Binary Search / Tree / Partitioning on unsortable data?

First, this question is not really about binary search as I neither have sorted data, nor any sortable data at all. :-) W.r.t the "unsortable" claim see below; but I think the title term "unsortable"...
247 views

### How to Simulate Control-Flow without using Control-Flow Primitives

Basically, I want to know how to simulate while and if if I'm handling the control flow myself through an array of instructions. The while loop can be simulated by if, as seen with assembly branching ...
160 views

### What is the complexity of find and checking prime numbers?

I'm trying to figure out the complexities of these two functions that I've written but could not understand.def First, I thought it is supposed be O(N). But it is not clear how many times the loop ...
1k views

### Adjacency List list of linked list or can be repesented in other ways?

I am new to graph data structure. Everywhere on google it is said to be list(or array ) of linked list. My question is can not it be represented as list of list(in java array list of array list) or ...
144 views

### Parnas' Paper on Modularization and Workflow Engines

In a Software Engineering class, we had an assignment to read Parnas' seminal paper on modularization [0]. In this paper, two approaches of dividing a software into modules are discussed: Traditional ...
770 views

### How to solve a Constraint Satisfaction Problem for Scheduling

This presentation describes several algorithms for solving a CSP for scheduling. Say I have a few processes with some constraints: a before c c before b b after d c 50% more important than e give d ...
165 views

### Alternative to the stable marriage / hospital residents solution?

I manage co-curricular programs for the school I work at. Until now, they have signed up on a google form on a first-in best-dressed capacity, but there is lots of complaints about how some students ...
92 views

### Generating combinations without getting stuck in recursive calls

This question is about figuring the design of a recursive function that changes the state of a group of elements by processing one of them at a time, with the goal of reaching a desired state. The ...
34 views

### Assembling random indexed packages into an ordered sequence(s)?

I am pretty confident that this is well-known and solved problem. Suppose there are n uniquely indexed "packages" randomly getting into single entry point like .AcceptPackage(Package package). ...
331 views

### Interdependent variables

Let's say there are two variables a & b, both a & b would have a value between a predefined range. a = x1 to y1 (range) b = x2 to y2 (range) Variable a & b are interdependent, if the ...
121 views

### Proof of digital document integrity

Let's say we have the following scenario. We have user A and user B and an initial digital document D generated by B. What algorithms and infrastructure are required in order to guarantee/prove ...
193 views

### Calendar scheduling: home field constraints

I am working on a round-robin scheduling algorithm for sports. The goal of the algorithm is to schedule all given games across different weeks, in the given fields and given game times. These are ...
126 views

### Help with algorithm for organaizing blocks

So I'm stuck on this problem for around a week, tried different approaches and having a hard time coming up with a solution. What I'm trying to achieve is to fit blocks horizontally inside another ...
280 views

### What is the SLOWEST 32 hashing function without excessive collisions

I am currently using a CRC32 hash to generate a locality sensitive hash for some of my data. For much the same reasons as PKBDF2 makes a better choice than, say, SHA26, for hashing passwords I ...
53 views

### Modified priority queue (with “disabled” elements)

I need something like a priority queue but with the following modification: Sometimes I need to mark some elements in the queue as "disabled". Disabled elements: temporarily (until marked non-...
129 views

### What tools exist to determine the speed up a GPU will have on an algorithm?

Basically, I am wondering what sort of speed I will get by parallelizing a algorithm to work with GPUs. I am wondering if someone has implemented queueing theory/Amdahl's law with a UI or if everyone ...
80 views

### Maximize picks from a list when you can only choose 2 items from every 7 items [closed]

What would be an O(n) algorithm to maximize picks from a list when you can only choose 2 items from every 7 items. I've been thinking about this problem for a few days and I can't figure out an answer....