Questions tagged [collections]

Collections APIs provide developers with a set of classes and interfaces that makes it easier to handle collections of objects.

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4
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1answer
74 views

General use multi-dimensional container using operator[]

This is a followup to a previous question of mine on same subject. Context I want to have a tool that allows to simulate as much as possible a C++ standard container for a multidimensional ...
4
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2answers
344 views

Non generic Skip List implementation in C++

Edit: This code was reworked and repostetd under a new question: Non generic Skip List implementation in C++ Version 2 To sharpen my C++ skills I tried to implement a skip list. I was quite happy ...
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2answers
90 views

Summing payments by year using Java Streams

I'm using 1.8.0_162 version of Java and here is my task about stream framework ...
8
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3answers
164 views

Build clusters from connections (virus propagation)

The scenario is the following: There is a list of persons and places where those persons visit. Each person is connected to a single or multiple places. See the picture below, where O[i] represents ...
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3answers
107 views

List mapping of large data set from file

I have a list of items 116 thousand and my mapping function is taking quite some time to process. I am using the file helpers library to write the CSV to disk but its the for each that is taking ...
9
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2answers
306 views

Multi-dimensional container using operator[]

This is a late followup to a previous question of mine on same subject. Context: I want to have a tool that allows to use all the C++ goodies (algorithms, for loop on containers, etc.) on a ...
2
votes
2answers
649 views

Wrapper for a raw array so that it can be passed to templates expecting Standard Library containers

I am working with a code base where unfortunately I cannot replace all raw arrays with std::array. The spec provides no guarantee that the memory layout of a ...
7
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1answer
139 views

Custom container for iterating over combinations of elements from multiple sets

Motivated by some SO quesitons [1, 2] I made an attempt at implementing a custom container with a bi-directional custom iterator for iterating over all combinations of elements from multiple sets. I ...
5
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2answers
65 views

Filter queries three orders of magnitude slower than insertions

As part of a C++ library, I'm implementing a filter class for approximate set membership and abundance queries. The filter has two primary operations: ...
4
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1answer
468 views

Fast insert unique container

I posted the same question at StackOverflow then I got an advice to post it here. Original question: https://stackoverflow.com/questions/49998297/fast-insert-unique-container I have to store ...
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3answers
98 views

Fill in workbook with data from another workbook

Followup to this question I made a macro that will fill in data in a workbook that has 65 (24 are user filled) columns and can go as long as 1500 rows. The macro can import about 1500 rows and 24 ...
3
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1answer
151 views

Finding the lowest possible number of changes to turn one string into another

I've been working on a task: I have two giant strings, both consist of the same characters just scrambled (both consist only capital english letters). The task is to find the lowest possible number of ...
4
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1answer
78 views

Fill a new Workbook with info from another workbook

I made a macro that will fill in data in a workbook that has 65 (24 are user filled) columns and can go as long as 1500 rows. In an ideal scenario, the workbook has a perfect column that could work ...
4
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0answers
117 views

C++11 Removable connection from emitter or receiver object

Please review my solution for the following problem. I am interested in: Maintainability Usability Logical correctness Efficiency Problem: It has 1+ objects each in separated thread and between the ...
5
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1answer
1k views

Complete ObservableDictionary

In conjunction with a recent question of mine, I found that an ObservableDictionary would be very handy for my situation, so I decided to implement one. I've ...
2
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2answers
900 views

Set, List and Map equality comparison with Lambda check

I'd like to be able to compare two objects with different equality checks. This should work if they're in a Set, List or ...
5
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2answers
5k views

Example of adding STL iterator support to custom collection class

I'm trying to create an example of a custom collection with an API meeting the requirements of STL iterator templates, as a learning experience. The collection used here, a ring buffer, is merely a ...
5
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1answer
117 views

C++ container — variable byte coded numbers list

I'm writing a container for unsigned integers, which uses variable byte coding. It works but some decisions I took look ugly so I would be glad if you gave me some hints for improving the design. I ...
0
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1answer
46 views

Create numerical-key array from existing string-key array, with a given string-key as first item

I have an array of available languages for my website, with a short ISO country code as the key for each language. I need to create a new array that contains the same info, but with numerical keys and ...
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2answers
1k views

Iterator of Container of Container

Based on this question I though I would pull together an iterator that iterated over a container of containers. ...
0
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1answer
1k views

Returning containers from function - C++ [closed]

I've been trying to implement a few interfaces for processing data. And most of the time I do new of container and return a smart pointer to this container. ...
3
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1answer
60 views

Python JIT container type

This is a follow on from this review. Where I am attempting to improve the performance of my rest client. I have created an container type (as suggested in my previous post) that lazily instantiates ...
0
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1answer
46 views

Find combinations of items in a nested collection

It's a very typical problem that I come across here and there. Imagine that you have a collection of items of any type, and sometimes items are collections themselves; you then need to "expand" them ...
1
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2answers
83 views

Given a list containing dates and the amount spent on each date, display the total amount spent per month

I had an interview yesterday where I was asked to write a function that would take in a list containing a date and the amount of money spent on that date, and to output the total amount spent per ...
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0answers
2k views

Custom dictionary class for reading and writing json value to a file

Is my implementation good? The program works as planned, but I wonder if some parts of the code can be made cleaner or more efficient. The file output looks like this: ...
0
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1answer
771 views

Scala type matching map

I was working with some complicated generics system, and I found the need to make an abstraction for a typesafe mapping between K[T] and V[T] where T is the same for individual pairs. In the case ...
5
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1answer
22k views

Map with case insensitive get, remove and containsKey

I am looking for a Map implementation (with String keys and any generic type for values) that would support getting, removing ...
2
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1answer
70 views

Getting single element or throwing one of two exceptions

Sometimes I need to get a single thing from a collection but I'm not very happy with the Single extension. It does not differentiate between empty and more than one ...
2
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1answer
731 views

VBA: Loop all .xlsx files in a folder and produce a list of worksheets and workbooks contained therein

I pieced together this code in answer to the following OP post on Stack Overflow: Get worksheet Names of All .xlsx files in a folder Task: The OP basically wanted to loop all .xlsx files in a folder ...
2
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2answers
157 views

Vector replacer

I rolled an own vector-like construct with improved performance and got it reviewed. Here is the updated version. ...
2
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1answer
2k views

Vector-like custom container with improved insert performance

I rolled a little container class (just for couriosity) which was meant to be able as a vector replacement in some cases. (Whoever wonders about the lack of move semantic etc, I just left it out due ...
5
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2answers
248 views

General FizzBuzz in Scala

I wanted to create a FizzBuzz implementation that both showcases the strengths of Scala (Functional paradigm and collections) and is general enough to anticipate the typical interview follow-up ...
1
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1answer
238 views

Array Wrapper Class

I’ve wrote a small array wrapper class which mimics the built-in Collection for adding and retrieving items. Once the object is created, you set the array capacity and that would not change. ...
2
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2answers
113 views

Optimise many namedtuple assignment statements [closed]

I'd just like to know if there's a way I can reduce the number of namedtuple assignment statements in the code below. The actual program has over 60 assignment ...
1
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1answer
3k views

Generic Comparator

I have tried to make a generic comparator with the use of reflection, but I am not sure how efficient it is or if it is the right way to do so Also, I don't know how it will handle dates. ...
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2answers
91 views

PHP port of Java collections

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0answers
538 views

Flattening a map into a list of records

In my everyday work I'm trying to move away from traditional iterating over collections to a more Java 8 streams-like behavior. I'm currently working on a project where I have a collection defined as: ...
4
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2answers
794 views

Implementing an HotelManager interface in Java

Got a mission to implement an Hotel Manager interface. I will post the interface and the attached class Reservation, and will add my code. What I am asking you is ...
2
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1answer
729 views

Filtering a log file and extracts by different properties

I have implemented a program to extract a log file which contains a header line, followed by zero or more data lines, in comma-separated value format. The file consists of 3 columns. The first column ...
0
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2answers
25 views

Removing objects from a list that don't appear in a list of ID's

I have a list of objects with each of them having an ID. I have a second list that is just a list of media ID's. I want to remove the objects from the first list that don't match a mediaID contained ...
1
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0answers
96 views

Purely functional octree and octree priority queue

I'm programming a game in Scala, and a lot of tasks are able to be done in the background. I've created a system in which each Future can be assigned a position in 3d space, and they are stored in an ...
1
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1answer
44 views

JointIterable: iterates over all elements of a list of collections

I have this small utility class that allows me to iterate over a series of collections. Please tell me anything that comes to mind. JointIterable.java ...
3
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1answer
116 views

Sorted vector/set class that works with simple types (char, int, double, etc…)

I'm new to C++ (approx. 3 months) and have just read Stroustrup's Programming Principles and Practice. Previously used Python a lot. As an exercise I tried to implement a custom container, with the ...
4
votes
3answers
408 views

Counting votes for candidates in a category and region

With the following code, I want to count the Vote objects from a collection, filtering on one of their fields, Candidate. I have the feeling that I can get this done much more efficiently. ...
1
vote
2answers
2k views

Variadic template class that stores a vector of each type given [closed]

I'm exploring the possibility to generalise a class of mine that stores some entities. I like it to be able to keep entities of several type, given as template arguments. To explore the possibilities ...
0
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2answers
123 views

User and group management access to main class

UserGroup is not the main class. I don't really mind putting these classes in a class as they are related. I would still like to break them out. Problem I have is if I put ...
2
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1answer
98 views

Unsafe collection which allows immutable access while also allowing push()

To get myself used to writing unsafe code, I wrote a collection which allows the user to keep immutable references to the elements of a vector while still being ...
3
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1answer
11k views

Generate JSON for Map<String, Map<String, List<String>>>

Consider I have a String: ...
2
votes
1answer
1k views

Method to return statistics from a collection with O(1) time and space

I have a DelayQueue, and the goal is to collect statistical information from the collection in O(1) time and space from ...
3
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2answers
864 views

Case insensitive string to replace custom comparers

In some solutions I use case-insensitive strings a lot and so far I've been always writing custom collections or using custom comparers to support them. This is usually a lot of work and a lot of ...

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