Questions tagged [hash-map]
A data structure that uses a hash function to map identifying values, known as keys, to their associated values
901
questions
2
votes
1
answer
20
views
Separate Chaining Hash Table Implementation in C++
I've implemented a separate chaining hash table in C++ and would appreciate any feedback or suggestions for improvement.
Code:
...
- 21
5
votes
2
answers
959
views
Optimized data structure mapping finite set of integers to values in C++
I'm looking for a mapping data structure, but knowing that the possible values of my keys are small numbers, I would like to trade memory for better performances (for both random access and value ...
- 611
3
votes
2
answers
138
views
Check for key in dictionary without magic value comparison
I'm using pydantic in a project to check file formatting for an object, as well as pylint for linting. Whenever I read a file with an invalid format, I want to raise an exception with a descriptive ...
- 33
-2
votes
1
answer
57
views
Multiple key swap algorithm [closed]
I have a dictionary with key - data pairs. My data comes from excel sheets. When I create the dictionary my objects are placed in order by their keys ex. 1 -> data of sheet1, 2 -> data of sheet2 ...
- 5
5
votes
1
answer
408
views
Optimizing Perfect Hash Table Implementation in C for Improved Performance
I wrote code that implements perfect hash table, according to its description in the book "Introduction to Algorithms by Thomas H Cormen", but the code does not pass time tests in contest. I ...
user282352
5
votes
0
answers
122
views
A new Dictionary for VBA
The latest version of the Dictionary class presented in this question is available in the VBA-FastDictionary repository under the latest release.
Motivation
I ...
- 1,511
4
votes
3
answers
268
views
Given two sparse vectors, compute their dot product
Problem Statement:
Given two sparse vectors, compute their dot product.
Implement class SparseVector:
SparseVector(nums) Initializes the object with the vector nums
dotProduct(vec) Compute the dot ...
- 81
6
votes
3
answers
699
views
Program that brute forces to find the minimum dominating set
This program solves the minimum dominating set but it takes an insanely long time to run. In case you do not know, in graph theory, a dominating set for a graph G is a subset D of its vertices, such ...
4
votes
2
answers
427
views
Map constructor utility class in Java 8
In a Java 8 project, I'm using several maps, many of which contain static or default content. In Java 9 and newer, there's the convenient Map.of() method and I want ...
- 583
1
vote
2
answers
92
views
Saving multiple files in python
I have this stupid code block below to save multiple files in Python. It is kind of repetitive (but it works). I was wondering how to improve it, notably:
Is it worth it to write a function for two ...
- 179
3
votes
1
answer
110
views
Simple hash table written in C with REPL
This is a simple hash table I've written in C. It is a closed-addressing hash table with TABLE_SIZE number of buckets. The hash ...
- 267
2
votes
2
answers
80
views
Dictionary additional function implementations
I've written a utility class BetterDict to help me on some of my other projects. I've implemented the &, ...
- 10.3k
5
votes
2
answers
777
views
1
vote
1
answer
102
views
5
votes
2
answers
267
views
C# console app that computes the Jaccard Index
So I wrote a basic C# console application that computes the Jaccard Index. This has its applications in cybersecurity and machine learning. Given two sets X and Y, the basic formula is:
$$ J(X, Y) = \...
- 183
1
vote
1
answer
104
views
An immutable class that contains Dictionary properties and needs a distinct hash code based on those Dictionaries
I have a Job class that represents jobs in a manufacturing system. The idea is that a job requires some quantity of certain materials, and it outputs some quantity ...
- 21
5
votes
1
answer
164
views
Set implementation
I believe reinventing the wheel is in fact a good learning exercise. How can I improve my Set implementation without just copying ...
- 581
2
votes
3
answers
343
views
A hierarchical dictionary for dotnet
Is there an existing class in .Net for representing and querying hierarchical data; i.e. providing methods which allow you to test whether one item is an ancestor or descendant of another, or to ...
- 1,409
3
votes
2
answers
137
views
Covid Data Base Hash Map in C++
This is a follow up question to Date Checking in C++
I have these two function prototypes:
void CovidDB::add_covid_data(std::string const COVID_FILE)
...
0
votes
2
answers
61
views
Checking which programs are used for scripting
I have a directory where there are some script files, some binary files, and some subdirectories. I have tried to write a program which gets names of all files in directory, and excludes if they are ...
- 251
4
votes
1
answer
134
views
Find the longest palindromic subsequence - Using a hashmap in Rust
This is a leetcode question which I wanted to solve using Rust as I'm learning Rust at the moment. I would appreciate some feedback on how to write it idiomatically.
Link to the question: https://...
- 307
5
votes
2
answers
2k
views
SHA-256 Hash with a short string length in javascript
I think I've found a way to somewhat "compress" the length of a SHA-256 hash. I am doing some addition, so I wanted to know whether an approach like this is secure or not.
...
- 101
4
votes
3
answers
174
views
quadratic probing hashmap and its time efficiency
I am writing small a hashmap library (not full featured yet) but I have some questions about the algorithm I wrote, the formula I hope I got right from wikipedia and general things.
Measured ~14.3 ...
- 351
2
votes
1
answer
47
views
Remove inputted keys separated by spaces from map and output the resulting map, including alias recognition
I'm looking to integrate Kotlin idioms (including code style) and maybe better performance. I wonder if there's a better way to do line 17 (the str.split(' ') one).
...
- 131
5
votes
1
answer
911
views
Merge multiple map with java stream api
I am trying to merge multiple map with Java stream API.
The reqiurements like ...
this method can receive multiple map, does not care hot many of it
support 2 merge method: intersection, union
if key ...
- 321
4
votes
2
answers
156
views
Sort a dict by keys, assuming keys are orderable
I found a suspicious code snipped in an existing project in which I am involved as a developer. The code sorts a dict by its keys, so that if iterated over the dict,...
- 161
7
votes
4
answers
1k
views
Calculate average values for each day of the week for each Meter
I have a program with these two methods. One method to import a set of data from a CSV within the given time period and store them in a dictionary. Here the data in CSV file is stored in following ...
4
votes
1
answer
3k
views
Merge two dictionaries
This function merges two dictionaries, using the value from the later dictionary to resolve conflicts.
I have 5 tests that the program passes successfully:
...
- 41
3
votes
3
answers
606
views
VBA Very Slow Performance using objects with scripting dictionary
I have a simple code that loops through a text file to fix a few things in it and I use mostly dictionaries to find and handle the adjustment. However, with larger files (about 30K lines) it seems to ...
- 31
3
votes
1
answer
285
views
C void* Generic Hash Table
Some time ago I tried to make a generic linked list in pure C (no external libraries, only the C standard library) using void*s here. Building on top of that and ...
3
votes
2
answers
2k
views
Implementation of Hash Function in C language
I'm new to programming. and I'm learning a C language. Currently working on Harvard's CS50 problem set (this one: https://cs50.harvard.edu/x/2022/psets/5/speller/).
In that problem, they want us to ...
- 133
4
votes
3
answers
2k
views
Switch case on an enum to return a specific mapped object from IMapper
I have an ever growing switch case statement I plan on adding 3 more case statements to. Given an int, compare it to an enum, and call ...
- 143
0
votes
1
answer
49
views
Count occurrence of elements in map during creation
This code works, but it's so ugly, so I was hesitant to put it on display.
There must be a nicer/easier way to achieve this.
The main issue is to count each unique occurrence during runtime when the ...
- 421
6
votes
1
answer
203
views
Creating a Dictionary<string,string> to generate the most frequent continuations (without Linq)
Main is added to compare the expected result with the result of the function, the war field is GetMostFrequentNextWords.
What ...
- 63
2
votes
1
answer
128
views
Write a function that takes a list of dicts and combine them
There is an exercise in the book Python Workout: 50 Ten-minute Exercises that asks to write a function to do the following:
Write a function that takes a list of dicts and returns a single dict that ...
- 123
2
votes
1
answer
209
views
Finger Exercise: Update book cipher by creating new book
I'm working my way through the finger exercises in John Guttag's book Introduction to Python Programming, third edition. The following finger exercise on page 143 describes encryption/decryption with ...
- 123
3
votes
1
answer
53
views
Optimizing code for this function that filters a JSON file
I made a function that turns all child from a JSON file to parents (or brothers?). It adds the parent name to the key, so there are no duplicates.
It works ok, but I would like to ask if there are ...
- 31
1
vote
2
answers
174
views
Parse list of UserPrincipal objects into custom class
I'm wondering how I could optimize this method that takes in a list of UserPrincipal objects, filters them by Regex and inserts the new class instance into a list. It takes 4 to 5 seconds for an input ...
- 11
3
votes
1
answer
118
views
Multiway map in C++
I recently had the problem that I wanted a hashmap where there would be a variable amount of distinct classes which each could be used to look up each other. I couldn't find any implementation online ...
- 149
0
votes
2
answers
112
views
Create all words that correspond to a telephone digit sequence
I wrote a terrible function to map E.161 keys to letter strings.
I think the logic could be simplified using a recursive function; however I have never been good at recursive methods. Any suggestions ...
- 109
1
vote
3
answers
171
views
Caesar cipher - Encode text from external file using HashMap Java
This is one of my school assignments and I just wanted to ask if there are some obvious mistakes or things I could maybe improve in this code.
Thank you for any suggestions.
...
- 11
1
vote
2
answers
159
views
Implementation of Hashtable in C99
I tried implementing a general purpose hashtable in C99.
The basic structure is I have a huge array of hashtable entries and each entry is the entry point to a doubly linked list so that in case there ...
4
votes
1
answer
1k
views
Transliterate between Cyrillic and Latin scripts
I want to get a code review on the following transliteration code. I wrote it because there were some libraries that I have tried and they were specifically failing with the name "Yuliya" ...
- 749
2
votes
1
answer
77
views
Implementation of JSON schem parser to extract some attributes
I have three different types of schema possibilities as below:
...
- 197
2
votes
1
answer
61
views
API request into a dictionary
I have the code below which currently pulls pricing data for Ethereum from CoinGecko API. From this request I am building a dictionary that contains the pieces of information and returning it to be ...
- 23
3
votes
1
answer
94
views
2
votes
1
answer
77
views
Processing charge current error messages with HashMap<>
I have certain error states that I am displaying in my Android TextView but only one message is displayed at a time and if all values are set to 0, no message is displayed. So, I check all the values ...
- 65
2
votes
1
answer
213
views
Finding anagram groups using hashing and mapping the alphabet to random numbers
I was solving Group Anagram problem in leetcode. Link for the problem https://leetcode.com/problems/group-anagrams/
Below is the code which I wrote
...
- 287
3
votes
1
answer
58
views
Implementation of building nested dictionary from list
I have a value test-1 and a list of keys as below:
...
- 197
2
votes
1
answer
145
views
Hash table C implementation - Separate Chaining
I've written a C implementation of a hashmap of strings including the basic operations and a strategy for handling hash collisons.
Additionally, I've included some tests, specifically for cases ...
- 137