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Questions tagged [data-structures]

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

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28 votes
7 answers
11k 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 ...
Chiron's user avatar
  • 4,543
87 votes
7 answers
65k 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 ...
Giedrius's user avatar
  • 1,314
15 votes
5 answers
10k views

Understanding Abstract Data Types (ADTs) [duplicate]

Just browsing through Code Complete last night and I came across the explanation of abstract data types. I must have read it 5 times, and the Wikipedia article doesn't help much either. So what I'm ...
billy.bob's user avatar
  • 6,549
13 votes
7 answers
20k 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? ...
Snow_Mac's user avatar
  • 349
105 votes
15 answers
120k 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 ...
46 votes
6 answers
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 ...
codebreaker's user avatar
  • 1,724
49 votes
4 answers
125k 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 ...
user avatar
17 votes
4 answers
30k 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 ...
mpasko256's user avatar
  • 346
14 votes
2 answers
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 ...
Anthony's user avatar
  • 900
5 votes
4 answers
2k 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), ...
trojanfoe's user avatar
  • 205
5 votes
2 answers
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 ...
Seer's user avatar
  • 155
4 votes
6 answers
3k 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 ...
billy.bob's user avatar
  • 6,549
1 vote
1 answer
631 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.
scerrecrow's user avatar
62 votes
1 answer
91k 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 ...
GladstoneKeep's user avatar
61 votes
11 answers
34k 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 ...
Mel's user avatar
  • 1,131
44 votes
8 answers
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 ...
Rachel's user avatar
  • 24k
44 votes
2 answers
51k 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 ...
Dennis's user avatar
  • 8,247
41 votes
12 answers
31k 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 ...
sushil bharwani's user avatar
38 votes
10 answers
83k 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 ...
sushil bharwani's user avatar
35 votes
8 answers
40k views

Is it a good practice to use smaller data types for variables to save memory?

When I learned the C++ language for the first time I learned that besides int, float etc, smaller or bigger versions of these data types existed within the language. For example I could call a ...
Bugster's user avatar
  • 4,023
24 votes
4 answers
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 ...
Ben's user avatar
  • 728
23 votes
6 answers
18k 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?...
dan_waterworth's user avatar
22 votes
3 answers
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?
zduny's user avatar
  • 2,653
22 votes
3 answers
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 ...
Rachel's user avatar
  • 24k
21 votes
3 answers
879 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 ...
Chuck H's user avatar
  • 321
20 votes
6 answers
3k 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 ...
user1936's user avatar
  • 652
20 votes
9 answers
11k 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 ...
user avatar
18 votes
1 answer
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 ...
Carcigenicate's user avatar
16 votes
4 answers
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 ...
Ray Toal's user avatar
  • 1,315
14 votes
8 answers
28k 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, ...
Bryan Boettcher's user avatar
13 votes
8 answers
51k 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 ...
Dynamic's user avatar
  • 5,746
13 votes
5 answers
7k 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 ...
anthonyvd's user avatar
  • 655
13 votes
2 answers
14k 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 ...
jds's user avatar
  • 1,102
11 votes
6 answers
18k 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?
user52343's user avatar
  • 221
11 votes
4 answers
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 ...
11 votes
4 answers
501 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 ...
Conrad Frix's user avatar
  • 4,155
11 votes
3 answers
8k 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 ...
Pops's user avatar
  • 4,113
8 votes
2 answers
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 ...
Lance's user avatar
  • 2,605
7 votes
3 answers
20k 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. ...
Aviv Cohn's user avatar
  • 21.4k
6 votes
4 answers
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 ...
MaiaVictor's user avatar
  • 5,830
6 votes
4 answers
3k 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. ...
SF.'s user avatar
  • 5,156
5 votes
5 answers
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 ...
germanfr's user avatar
  • 181
5 votes
2 answers
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 ...
SF.'s user avatar
  • 5,156
5 votes
2 answers
8k 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 ...
ssc327's user avatar
  • 161
4 votes
3 answers
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, ...
GregRos's user avatar
  • 1,743
4 votes
4 answers
867 views

Why use an enum to determine node type in a parse tree?

The Sun Compiler Tree API uses an interface called Tree as the parent of all the different kinds of parse tree nodes (assignments, if-statements, class declarations, etc.). A part of this interface is ...
Alex Reinking's user avatar
4 votes
6 answers
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 ...
Rayhunter's user avatar
  • 151
4 votes
3 answers
1k 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 ...
miroxlav's user avatar
  • 672
4 votes
1 answer
2k views

How to store data that is recorded with different frequency?

I'm writing a metallurgical web application, that must store data (electrical parameters) recorded at different frequencies. For example: six parameters recorded with frequency of one measure per ...
trejder's user avatar
  • 2,396
3 votes
1 answer
4k 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 ...
Sam's user avatar
  • 413