Questions tagged [hash-map]
A data structure that uses a hash function to map identifying values, known as keys, to their associated values
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Hashtable implementation in C
I start to implement the function hashtable insert :
The function must be inserted by adding the node to the correct linked list if the key does not exist, or by replacing the value of the correct ...
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Making a generic NSMapTable replacement written in Swift thread-safe
This is a follow-up to this question.
While discussing some details about the code I posted there, I came upon a problem with thread-safety. After searching and trying different things, I reached a ...
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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 ...
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Dictionary additional function implementations
I've written a utility class BetterDict to help me on some of my other projects. I've implemented the &, ...
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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 ...
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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) = \...
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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 ...
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Set implementation
I believe reinventing the wheel is in fact a good learning exercise. How can I improve my Set implementation without just copying ...
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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)
...
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Bidirectional map based on memory manipulation
This is a bidirectional map implementation that stores the values as pairs on the heap, and uses pointer arithmetic for efficient lookup.
codepad link, may be easier to read
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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 ...
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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.
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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://...
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Simple string hashing algorithm implementation
I thought of a simple way to hash a string. By taking the ASCII decimal value of each character, multiplying it by 10, and adding all of the values computed together for each character in a string. Is ...
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Implementing hash table
I am implementing a program to interact with hash table, the data to be hashed is just number. It works but I want to know if there is any error like: memory leak,... in my code and how to improve my ...
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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 ...
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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).
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Get value from dictionary given a list of nested keys
I would like to get a deeply-nested value, for example {"a":{"b":{"c":"myValue"}} by providing the keys to traverse. I tried chaining together .get() but that didn'...
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Langton's Ant cellular automaton in Java
I made a couple of little games and cellular automata in Java. For every new 'game', I used the same code as a base, except for the game logic of course. With every iteration of me customizing my ...
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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 ...
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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,...
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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 ...
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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:
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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 ...
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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 ...
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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" ...
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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 ...
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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 ...
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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 ...
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Dictionary as context manager
I've created a class that implements customized addition, subtraction, etc. But for this class I'd like to have some additional parameters for these methods (__add__...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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.
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Efficient renaming of dict keys from another dict's values - Python
I have a dictionary in Python (uglyDict) that has some really un-cool key names. I would like to rename them based on values from another dictionary (...
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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 ...
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Check for null/empty in dictionary
I am doing the following about 10 times with other strings, so the code is duplicated. How can I refactor this?
queryWhere is a ...
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Implementation of JSON schem parser to extract some attributes
I have three different types of schema possibilities as below:
...
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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 ...
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Recursively merge n-level maps of values and lists
I was looking for a solution for a way to easily merge maps of serialized Yaml and came up with this.
Reference to a similar question (not asked by me):
https://stackoverflow.com/questions/25773567/...
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Cleanly modifying values in hashmap for a k-sum challenge
Just started learning Rust and here's a program that has caused me some agony to implement in Rust. This is very easy to implement in C++, but Rust's borrow checker is causing all sorts of trouble. My ...
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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 ...
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