Questions tagged [data-structures]

Questions regarding efficient storage and representation of data within a software application.

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28
votes
7answers
10k views

Should I keep investing into data structures and algorithms? [closed]

These days, I'm investing heavily in data structures and algorithms and trying to solve some programming puzzles. I'm trying to code and solve with Java and Clojure. Am I wasting my time? should I ...
77
votes
6answers
55k views

EAV - is it really bad in all scenarios?

I'm thinking to use an entity-attribute-value (EAV) model for some of the stuff in one of the projects, but all questions about it in Stack Overflow end up to answers calling EAV an anti-pattern. But ...
13
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7answers
19k views

How important is studying algorithms and theory is to becoming a great programmer? [duplicate]

Possible Duplicate: Should I keep investing into data structures and algorithms? I'm a CS student. I want to become a really great programmer, what do I need to do to be come a great programmer? ...
106
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15answers
119k views

Why are data structures so important in interviews? [closed]

I must confess that I was not so strong in data structures when I graduated out of college. Throughout the campus placements during my graduation, I've witnessed that most of the biggie tech companies ...
45
votes
6answers
7k views

How necessary is it to follow defensive programming practices for code that will never be made publicly available?

I'm writing a Java implementation of a card game, so I created a special type of Collection I'm calling a Zone. All modification methods of Java's Collection are unsupported, but there's a method in ...
43
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4answers
112k views

Abstract Data Type and Data Structure

It's quite difficult for me to understand these terms. I searched on google and read a little on Wikipedia but I'm still not sure. I've determined so far that: Abstract Data Type is a definition of ...
13
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2answers
6k views

Amortized Analysis? (Worst-case Performance Guarantees)

What is Amortized Analysis? And how can it help me achieve worst-case performance guarantees in my programs? I was reading that the following techniques can help the programmer achieve Worst-case ...
15
votes
4answers
23k views

Is storing a list of strings in single database field a bad idea? Why?

Recently, I started to work on some legacy system. People that developed it, came to an idea to store list of strings in single field of database table. Lets say that it is an identifier for object ...
5
votes
2answers
7k views

Name of data structure that's tree-like with multiple root nodes

I'm attempting to implement a data structure, and using a more traditional tree data structure, but I'm not using the root node as it holds no real value in the context I'm using it in. Ideally, I ...
4
votes
4answers
1k views

Search algorithm with co-ordinate (x,y) hints?

I am about to start writing a UI view where many small text items are laid-out over the view and when the user hovers over a text item a dynamically-generated image is displayed (like a tooltip), ...
4
votes
6answers
2k views

Why isn't the line count in Visual Studio zero-based? [closed]

This just struck me as an oversight by Microsoft. Since arrays and other data-structures within the .NET framework begin from zero (zero-based) why don't we have a line 0 within the code view in ...
1
vote
1answer
543 views

Is a linked list an actual data structure?

I hear conflicting sides from this topic. I was under the impression that a linked list was a way to implement a data structure (stack, queue), not actually a data structure.
38
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10answers
82k views

How do I learn algorithms and data structures? [closed]

This is in continuation to my previous question where I asked is it necessary to learn algorithms and data structures. I feel yes it is. Now I work in an environment where I won't ever get the chance ...
55
votes
1answer
70k views

Treating a 1D data structure as 2D grid

I am working with a native class that represents a 2D image as a 1D array. If you want to change one pixel, for example, you need to now how to derive the index from the x,y coordinates. So, let's ...
41
votes
12answers
30k views

Do I need to understand algorithms and data structures to be called a programmer? [closed]

It has been six years since I have been coding. Coding into all kinds of things like ActionScript, JavaScript, Java, PHP, Ajax, XML HTML, ASP, etc. I have used arrays, maps, linked lists, sets, etc ...
59
votes
11answers
30k views

How to represent a Rubik's Cube in a data structure

If I am attempting to simulate a Rubik's Cube, how would you create a data structure to store the cube's state in memory, with X number of tiles per side? Things to consider: the cube can be of any ...
42
votes
2answers
46k views

PHP: when to use arrays, and when to use objects for mostly-data-storing code constructs?

PHP is a mixed paradigm language, allowing to use and return non-object data types, such as arrays. I pose a question to try to clarify some guidelines for selection of arrays vs objects when deciding ...
19
votes
6answers
2k views

How did we get saddled with the (hierarchical) filesystem as the basic data structure?

I'm self-taught and I don't have a CS degree. The more I've been learning about data structure, the more I wonder, in this day and age, how are we still saddled with the filesystem, with directories ...
12
votes
4answers
6k views

What are the differences between algorithms using data structures and algorithms using databases?

The General Question What are the differences between algorithms using data structures and algorithms using databases? Some Context This is a question that has been bugging me for some time, and I ...
17
votes
1answer
4k views

How does a skip list work?

For a homework assignment, I need to understand how a skip list works. I've been programming for a little over 2 years now (I know that's not that long in reality), and I have never even heard of a ...
24
votes
4answers
1k views

What is the definition of "Big Data"?

Is there one? All the definitions I can find describe the size, complexity / variety or velocity of the data. Wikipedia's definition is the only one I've found with an actual number Big data ...
18
votes
9answers
10k views

Data structure for accessing units of measure

TL;DR - I'm trying to design an optimal data structure to define units within a unit of measure. A Unit of measure is essentially a value (or quantity) associated with a unit. SI Units have seven ...
11
votes
8answers
50k views

What is the difference between an Array and a Stack?

According to Wikipedia, a stack: is a last in, first out (LIFO) abstract data type and linear data structure. While an array: is a data structure consisting of a collection of elements (values ...
20
votes
6answers
15k views

Which self balancing binary tree would you recommend?

I'm learning Haskell and as an exercise I'm making binary trees. Having made a regular binary tree, I want to adapt it to be self balancing. So: Which is most efficient? Which is easiest to implement?...
13
votes
2answers
13k views

What is the relationship between data structures and algorithms? [closed]

I have been searching for a good online course in data structures but have found that Google also returns results for algorithms courses, which say stuff like: In this course you will learn several ...
4
votes
2answers
5k views

Store and Tag Millions of Images

I am building an application where I need to store millions of images and later tag them. The tags attributed to the images could change over time as the tagging system evolves. Images will then be ...
44
votes
8answers
7k views

How should I build the data structure for a dynamic, unlimited-size "maze"?

I'm not actually sure that "maze" is the correct term. Basically users start in a single Room that has 4 doors (N, S, E, and W). They can go in any direction, and each subsequent room is contains ...
21
votes
3answers
873 views

How do I express subtle relationships in my data?

"A" is related to "B" and "C". How do I show that "B" and "C" might, by this context, be related as well? Example: Here are a few headlines about a recent Broadway play: David Mamet's Glengarry ...
20
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3answers
3k views

When programmers talk about "data structures", what are they referring to?

When programmers talk about "data structures", are they only talking about abstract data types like lists, trees, hashes, graphs, etc.? Or does that term include any structure that holds data, such ...
12
votes
5answers
6k views

Data structures in functional programming

I'm currently playing with LISP (particularly Scheme and Clojure) and I'm wondering how typical data structures are dealt with in functional programming languages. For example, let's say I would like ...
8
votes
2answers
1k views

How do personal assistants typically generate sentences?

This is sort of a follow up to this question about NLG research directions in the linguistics field. How do personal assistant tools such as Siri, Google Now, or Cortana perform Natural Language ...
22
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3answers
4k views

How do purely functional programming languages deal with fast changing data?

What data structures can you use so you can get O(1) removal and replacement? Or how can you avoid situations when you need said structures?
6
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3answers
17k views

Why is the complexity of fetching a value from an array be O(1)?

How come the complexity of fetching a value from an array by it's index is O(1)? I thought the algorithm has to go through all the indexes, find the correct index, and then know what value to return. ...
11
votes
3answers
6k views

How to represent a graph with multiple edges allowed between nodes and edges that can selectively disappear

I'm trying to figure out what sort of data structure to use for modeling some hypothetical, idealized network usage. In my scenario, a number of users who are hostile to each other are all trying to ...
6
votes
4answers
3k views

Why many programming languages have only 2 data-structures: arrays and hashes?

Many programming languages have only those 2 structures, and even some languages that have more structures still only provide special syntax for those 2; usually, [] and {}. Why is this? Is there ...
5
votes
2answers
4k views

Creating huge decision tree

I'm to write an event correlator. A fundamental part of the system will be a decision tree that recognizes the origin of the fault basing on recorded states and log files. Often many accidents will ...
4
votes
3answers
2k views

Internal Mutation of Persistent Data Structures

To clarify, when I mean use the terms persistent and immutable on a data structure, I mean that: The state of the data structure remains unchanged for its lifetime. It always holds the same data, ...
3
votes
3answers
3k views

Separating Code into Smaller Files in C

I am in the process of cleaning up my code and making it easier to maintain. I am doing this by turning my 5000+ line file into separate smaller files. I have successfully created separate source and ...
16
votes
4answers
3k views

Uses of persistent data structures in non-functional languages

Languages that are purely functional or near-purely functional benefit from persistent data structures because they are immutable and fit well with the stateless style of functional programming. But ...
14
votes
8answers
25k views

Practical way to store a "reasonably large" amount of data that hardly ever changes?

Think in terms of pre-computed lookup tables or something. At what point does it make more sense to use a database instead of hardcoding values in my application? The values are not going to change, ...
11
votes
6answers
15k views

What do you call classes without methods?

What do you call classes without methods? For example, class A { public string something; public int a; } Above is a class without any methods. Does this type of class have a special name?
4
votes
6answers
12k views

Heap overflow vs stack overflow

So as a general rule to avoid a stack overflow, big objects should be allocated to the heap (correct me if I am wrong). But, since the heap and the stack expand towards each other, wouldn't this cause ...
2
votes
1answer
3k views

Implementing tags in object

In my app, I'm implementing a questionnaire system and I'd like to implement tags for questions -- very similar to tags in questions here or Stack Overflow. I wanted to get some advices on how to ...
11
votes
4answers
497 views

Why is it that MS Data Access story is so fractured ? Is it the nature of Data Access or is just MS?

This StackOverflow question asks "where can I get Microsoft.Data.Objects" It turns out the answer was probably that its in the CTP4 (code first) release of Entity Framework 4 However there where a ...
6
votes
4answers
2k views

Representing a rule in a ruleset

How to represent rules for a rule engine as objects? A rule would be if (booleanExpression(input)) then a chain of generic actions" else next rule ...where the generic actions might be e.g. ...
5
votes
5answers
3k views

How to store math expression in c++ list

I am parsing a infix math expression to a postfix form. I want to store it in a list like [4.5, 3, 0.25, +, -] so that I can process it once it's parsed. I could store it in a string again, but I ...
4
votes
2answers
843 views

C#/VB struct – how to avoid case with zero default values, which is considered invalid for given structure?

How to implement some constrained .NET struct/structure (let's say LimitedString), where its state with default values (set by CLR to technical defaults, i.e. nulls, zeros, etc.) should be prohibited ...
4
votes
4answers
601 views

Building a route creator

Ok, already up front, I'm going to tell you, that this is a bonus task for Data structure course I'm taking. That should take care of all the questions whether or not this is for a homework. Route ...
2
votes
1answer
703 views

Closest location - Heapify or Build-heap

So lets say we have a set of gps data points and your current location. If asked to give the closest point to your current location we can utilize a heap with the distance being the key. Now if we ...
2
votes
1answer
444 views

Caching in '3D' - data-structures and octree recursion - hrrm!

The Situation: I have 68GB of data that is conceptually realized as a 3D matrix of 8-bit values with dimension 4096*4096*4096. I need to access multiple sections of this data for processing in a ...