A hash table is a data structure used to implement an associative array (a structure that can map keys to values). It uses a "hash function" to compute an index into an array from which the value can be found.

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Finding all integers in an array with odd occurrence

I am doing an interview exercise problem from here. The problem is to find "all numbers that occurred an odd-number of times in an array". Here is my high level psuedo code thinking: Construct a ...
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1answer
62 views

Thread Safe Objects in CSharp - ConcurrentDictionary

I'm using ConcurrentDictionary to hold the records.. I'm reading files from the local system in parallel, to speed up the process. Sample 1: ...
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1answer
66 views

Dictionary with restricted keys

I'm currently building some software that works with systemd unit files, and I've been trying to improve how we construct the unit files. This is all running in Python 3.4 This first block is the ...
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107 views

Replace keys in values with key->values from same dictionary

I have a dictionary whose values may contain keys that are already in the dictionary. What we are actually talking about are parameters. Sometimes a parameter is defined by a number plus another ...
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1answer
36 views

LRU Cache Design using LinkedHashMap

This is a follow-on qestion from: LRU cache design Revised Implementation ...
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73 views

Optimizing this method (HashSet.RemoveWhere performance issue)

I have the following method: ...
5
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0answers
47 views

BiDirectional Dictionary (and its Mutable friend can come too)

I've attempted to implement a 1-to-1 dictionary in Objective-C. I'm probably missing some convenient methods that one might commonly want to use. These are both declared in the same ...
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1answer
41 views

Simplifying the code with same list comprehensions

I have such method where: primary_images is dict, additional is ...
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1answer
57 views

Hash table with double hashing

I writing a hash table with double hashing. This code works ONLY with ASCII text files and finding the number of occurrences of each word in input file! Please point out mistakes and shortcomings. ...
2
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1answer
44 views

Use of dictionary for file-saving function

I have the following function: ...
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2answers
55 views

VSTO Write Dictionary To Range Extension Method

I was hoping to receive some criticism on this block of code. I wrote it to write the contents of a dictionary to excel range in VSTO. It works well. I am interested to see how people could improve ...
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1answer
39 views

Filtering stocks by dividend yield

I have a dict of stock tickers (KEY) and a data point (VALUE; e.g. dividend yield). I want to know which tickers have a value between a specified min and max value. Given ...
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3answers
145 views

Optimize huge text file search

I have several huge 100MB text files that I need to scan through to pick out certain frame numbers which relate to a specific log packet of interest. My plan was to scan for these frame numbers and ...
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1answer
50 views

Hashing a struct in C

I'm trying to learn how chained hashing works, but can't get any further than this. I think hashing works, but after finishing this little program, someone told me that what I have created so far has ...
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1answer
45 views

Handling overwriting of unique Dictionary values

I am working in C# to write a scheduling application for operations in a factory. I have a custom class Workday, with properties to represent a ...
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0answers
49 views

Hash Table Implemented by Javascript

I recently tried to implement a simple hash table using Javascript. Could anyone help me review my implementation? ...
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2answers
99 views

Counting a cycle

An interview question I got - Each element of an int array points to the another element, eventually creating a cycle. Starting at ...
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1answer
51 views

Iterating and fetching values from dictionary

Here is my dictionary: c_result1 = {"1": {"time": "89.46%"}, "2": {"date": "10.54%"}} c_result2 = {"1": {"money": "89.46%"}, "2": {"finance": "10.54%"}} I want ...
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2answers
68 views

Ruby hashes of status counts

I have a method that takes a model object, reads through its children and returns a hash of status counts. It should only return a count on a status if one exists. This method works, but I was ...
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1answer
58 views

A double mapped cache with WeakReferences for second key type

I needed a way to cache a large number of objects with two different types of keys. In my case: A String key represents my object in a serialized form. This way ...
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1answer
75 views

Determining the existence of string Intersections

Problem: Given 2 strings, consider all the substrings within them of length len. Len will be 1 or more. Returns true if there are any such substrings which appear in both strings. Compute ...
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1answer
69 views

Getting key-value from Object in Java

This takes a collection of Objects from JavaScript and puts them into a Java project. How can I improve this code? What's the best solution? ...
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2answers
159 views

Map String to list of string

Input: String : Title; List Tags Problem statement: Need to map title to tags, e.g. title is "china man japan beijing bell" and tags are ...
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1answer
93 views

Follow-up 2 to Morse Code String

This is my second follow-up. Major changes made: Use a Map instead of an enum for the Morse Characters Added ...
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3answers
223 views

Recursive Insertion in Hash Table (Linear Probing)

I was practicing implementing a hash function. I tried to use linear probing to insert in hash table. The insertion is working alright but I am not satisfied with the recursion. It doesn't feel like ...
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0answers
49 views

Finding Facebook Friends on app, and not on app

This code gets all of a user's Facebook friends who use our app and returns a dictionary with keys that are their id's in our database and values that are a default connection level. The code should ...
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2answers
81 views

Split a Map into sublists

I may get a Map of many many items that needs to be requested to an API. In order to improve performance, I thought about splitting that list into smaller ...
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4answers
83 views

Merge two dict in separate list by id

I have following data structure >>> a = [{'id': 1, 'name': 'a'}, {'id': 2, 'name': 'b'}] >>> b = [{'id': 1, 'age': 12}, {'id': 2, 'age': 21}] I ...
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1answer
59 views

Mapping yielding lots of warnings in use

Recently, I wrote a C header file that defines a new type called HashMap that allows for the storage of key/value pairs. I am just learning about the wonders of ...
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2answers
281 views

HashTable implementation

I have been trying to implement the Hash Table function in Java and here is what I came up with. I would just like to get an opinion on this work. Would there be a better way or any improvement to ...
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2answers
112 views

Hash Binary Tree Map

I made a map based on a binary tree ordered by hashcodes, with collisions fixed with equals(). Are there any improvements I could make? ...
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1answer
138 views

Regex matching keys in a Dictionary

I have extended this class http://wiki.unity3d.com/index.php/CSharpMessenger_Extended to accept strings containing wildcards as eventTypes, therefore I am able to ...
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1answer
54 views

Spatial hash triangles from multiple assets

I am implementing the spatial hashing algorithm described in Optimized Spatial Hashing for Collision Detection of Deformable Objects with a few adjustments, the largest one being that each bucket in ...
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0answers
39 views

Weeding out triangles for triangle-triangle collision detection using a spatial hash

I am implementing a multi-phase collision detection system whose final collision check is checking the triangles of one shape against those of another. As the number of triangle-triangle comparisons ...
3
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1answer
54 views

Finding average word length in a given year

I have written a function which takes the year in question and words as a data which is a dictionary that maps words to the list of year/count. Now I am wondering how I can improve the code that I ...
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4answers
546 views

Strategy pattern - design hash table

My programming skill has gotten rusty, so I would like to elicit constructive criticism that can make me write code better. I know the standard design is to use templates, and even obtain the hash ...
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2answers
389 views

Swift complexities with Dictionary

I have been trying to learn the various aspects of the languages I know so far to do the Daily Challenges in reddit (/r/DailyProgrammer). The one which I am working on just now asks for an ...
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1answer
146 views

Flattening a HashMap of (String → ArrayList) to an ArrayList

I have one HashMap<String, ArrayList<String>> and I want to concatenate a key with every item in its ArrayList. ...
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2answers
86 views

Sorting array with respect to two properties

I'm sorting with respect to Width and Length. However, Width has the significance ...
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1answer
75 views

Dictionary Key look up with variable length inputs

I am decoding GS1 barcodes and need to match up application identifiers with relevant data about them. ...
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2answers
96 views

Convert Object Keys according to Table/Map object

I have implemented a recursive function that converts an object's keys according to another lookup table/map. You are able to convert back and forth using the 3rd ...
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2answers
90 views

Make a dict class from scratch in Python

Here's the API my teacher assigned: and here is what I came up with: ...
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3answers
242 views

Map with different types for values

I am trying to implements a map (that can work as a cache) that has strings as keys and values of different types. In my real case once set the key/values in the map will not change. I used these ...
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2answers
140 views

Chained hash table implementation

While reading a data structure book, I have implemented a chained hash table. I want to share the code with you and get your opinion about it. chained_hash_table.h ...
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2answers
101 views

Fetch plist file

I have a plist file with many nested dictionaries inside of it, and I wanna fetch them all to my code. Isn't there any more efficient way to do that than nested for-loops? ...
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1answer
33 views

Generating a complicated data structure in a more efficient manner

I need to convert some CSV data into a format recognizable by some old script my work uses. Changing the format is pretty much out of the question. So I've written this: ...
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1answer
396 views

Dictionary (with silly hash)

Based on this question (but fixed so it can run). I have kept the code as close to the original as possible. I have Marked all the changes with Loki (should be easy to spot). Code here is written in ...
10
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2answers
418 views

Implementation of fixed size hash map

I'm trying to brush up on my algorithms and data structures and wrote a fixed sized hash map assuming both key and value will be only integers. This is a significant simplification of the real case ...
5
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1answer
60 views

Python DictionaryTagger class takes too long to initialize

With big inspiration from code from different webpages, I have created this DictionaryTagger. My problem is that it takes around 2 sec. to initialize the taggers / ...
2
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1answer
43 views

Print dict with varying-length lists

Is there a shorter way of taking a dict with varying length lists and printing it to screen? Shortcomings of this method also include that values which aren't lists are printed as letters separated by ...