Questions tagged [scala]

Scala is a general purpose programming language principally targeting the Java Virtual Machine. Designed to express common programming patterns in a concise, elegant, and type-safe way, it fuses both imperative and functional programming styles.

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25 views

how should I optimise the scala code and make it more readable

I have this ugly massive piece of code. It does many things, mostly around querying databases. Each query depends on the result of the previous query or on the parameters of the incoming request body. ...
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1answer
73 views

A simple data class based on an existing collection (Scala)

I'm fairly new to Scala and I would like to learn it properly. My current task is to create a type to represent a heap, as seen in interpreters: a mapping from addresses in memory to values stored ...
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1answer
57 views

What is better to use for mapping value to Map of functions: tail recursion or foreach?

I want to map functions from my functions library (Map called as chain) to input string str. ...
4
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1answer
66 views

Clean up tags from a text

I need to generate random text for tests. I do that using alphanumeric characters and some special characters as well. For some special cases, I cannot generate the random text with tags. I have the ...
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1answer
45 views

Integrating caliban, ZIO and Akka

I created a small sample project using caliban, akka-persistence and ZIO. I'm not really happy with the wiring code: ...
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1answer
40 views

implementation of atoi in scala

I've implemented atoi function as described in leetcode problem string-to-integer-atoi. I am looking for some feedback on writing this in a more scala native way ...
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143 views

generic implementation approaches for a recursive function

Let's take the famous fibonacci problem as an example but this is a generic problem. Also, taking scala as the language as it's rather feature-rich. I want to know which solution you'd prefer. we all ...
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1answer
47 views

Scala graph coloring

i have solved this problem https://leetcode.com/problems/find-eventual-safe-states/submissions/ ...
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0answers
37 views

Finite automaton library in Scala including subset construction and minimization

I built a scanner generator like flex or jflex in Scala for a class last year. Part of this project is a small library for handling and manipulating finite automata. It works completely as intended, ...
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1answer
53 views

Functional filter unique elements in sequence is not as good as imperative [closed]

Can you please help me fulfill the following? Requirements: Create an iterable with unique elements. Their order should be preserved: a | b | a | c → a | b | c ...
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57 views

Bellman-Ford Implementation in Scala/Java

I think the part to get shortest path from the cost table got pretty messy. Also can use some tips on how to avoid the extra O(V+E) work checking all edges from source to dest after getting the cost ...
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1answer
148 views

Perfect Number usage in higher order function

I am new to Scala. I have been trying to complete an exercise where the ask was as follows: // Write a function isPerfectNumber which takes integer input and returns String output. // It finds if a ...
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0answers
48 views

Synchronous use of Mongo-Scala Driver

The Mongo-Scala Driver (v2.6) currently only supports asynchronous operations, although my use cases often seem to lend themselves well to synchronous reads. This may be to block downstream code ...
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1answer
371 views

Dotty 0.19 (Scala 3) features: contextual abstractions

tl;dr I tried to write some as general and as feasible as possible code where entities are able to communicate with other entities of the same type or of different types, allowing for the recipient ...
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2answers
179 views

Scala app to transpose columns into rows

This is the first application or really any Scala I have every written. So far it functions as I would hope it would. I just found this community and would love some peer review of possible ...
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1answer
67 views

Create JIRA ticket using REST API

Objective: The objective of the program is to create a JIRA ticket using a REST API. It's working perfectly fine without any issue. However I am not sure if it's up to good Scala standards. I would ...
2
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1answer
127 views

Return all anagrams for a word matched against a list of words in a file

The exercise description: Given a ‘words.txt’ file (attached) containing a newline-delimited list of dictionary words, please implement a small command line application capable to return all ...
3
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1answer
60 views

Counting bigrams in XML files in a directory tree

I've written this code in Scala that extracts bigram statistics from the Reuters dataset. It puts the statistics in a Map[String, SortedMap[String, Int]]. For ...
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1answer
79 views

Provide functional-programming style solution for 2D Array - DS challenge

Problem Statement: Given a 6×6 2D Array, arr: 1 1 1 0 0 0 0 1 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 We define an hourglass in A to be ...
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1answer
144 views

Imperative and functional-programming solutions for Jumping on the Cloud challenge

Problem Statement Emma is playing a new mobile game that starts with consecutively numbered clouds. Some of the clouds are thunderheads and others are cumulus. She can jump on any cumulus cloud ...
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2answers
154 views

Count character 'a' in first n characters of indefinitely repeating string s

Problem statement: Lilah has a string, s, of lowercase English letters that she repeated infinitely many times. Given an integer, n, find and print the number of letter a's in the first n ...
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2answers
136 views

Counting valleys traversed below sea level, given elevation changes

Problem Statement: Gary is an avid hiker. He tracks his hikes meticulously, paying close attention to small details like topography. During his last hike he took exactly steps. For every step ...
4
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1answer
68 views

Print a Connect 4 grid based on some rules for each cell

In a game of Connect4: we start with an empty grid two players place pieces X and O on the grid the first player to achieve 4 pieces in a line wins! this is a text based console game Here is the ...
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1answer
48 views

Perform KS-test on Random Number Generator [closed]

I've just started practicing Functional Programming in Scala in some days. This is the code I used to perform KS-test on a random number generator. ...
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1answer
64 views

Is it possible to DRY these 2 methods of a tailrec Node Tree?

I have a Tree structure composed by Node class. I have to @tailrec method that are visiting up to the root. Those 2 methods ...
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3answers
138 views

Computing average duration per user from a large CSV file that doesn't fit in memory

We have a large log file which stores user interactions with an application. The entries in the log file follow the following schema: {userId, timestamp, actionType} where actionType is one of two ...
5
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1answer
587 views

Extracting numeric values from a string containing key:value pairs

I am writing function numericValues(text: String): List[Int] to extract patterns """([a-z]+)\s*:\s*(\d+)""" and return the list ...
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1answer
42 views

Page download with reattempts in Scala

I wrote the following code to deal with possible network problems. ...
3
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2answers
99 views

Solve membership binary mask problem in Scala

Imagine you have two string sequences: val s1 = Seq("c", "a", "b", "z", "a", "b") val s2 = Seq("a", "b") You need to come up with an algorithm that generates a ...
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0answers
54 views

Java classes to load configuration data from a JSON file, with Scala tests

I want to implement classes in a project that will support the loading of configuration data from a JSON file. The JSON file is in the following form. Please be as critical as you can be. I'm a junior ...
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2answers
82 views

Count Substrings for a binary string

Problem is taken from leet code. Give a string s, count the number of non-empty (contiguous) substrings that have the same number of 0's and 1's, and all the 0's and all the 1's in these substrings ...
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0answers
123 views

KMP algorithm in scala

I implemented KMP pattern matching algorithm in Scala. My code works but it looks more imperative and a scala translation of C/C++ implementation. I am not able to figure out how to manage multiple ...
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1answer
83 views

Find first repeating Char in String

Given a string, find the first repeating character in it. Examples: firstUnique("Vikrant")None ...
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2answers
46 views

Expand spreadsheet ranges to lists of cells in Scala

Problem Spreadsheet cells are referenced by column and row identifiers. Columns are labeled with alphabetical characters, starting with "A", "B", "C", ...; rows are numbered from 1 in ascending ...
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1answer
94 views

Minimum steps to reach target by a Knight In Scala

Given a chessboard of N size (square matrix), the position of Knight and position of a target, find out minimum steps (both count and exact steps) from start to target for a Knight. If it is not ...
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0answers
68 views

Closest 3Sum in Scala

This question is taken from Leet code. Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three ...
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2answers
86 views

Replace array element with multiplication of neighbors in Scala

Given an array of integers, update the index with multiplication of previous and next integers, Input: 2 , 3, 4, 5, 6 Output: 2*3, 2*4, 3*5, 4*6, 5*6 Following ...
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1answer
271 views

Clockwise rotate a matrix in Scala

Given a matrix, clockwise rotate elements in it. Examples: ...
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2answers
198 views

Print matrix in spiral order in Scala

Problem: Given a square or rectangular matrix, print its element in spiral order. For example, if input matrix is this: ...
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1answer
183 views

Print words in decreasing order of frequency in Scala

Given a string print its words in decreasing order of frequency. Example: i/p - "aa bbb ccc aa ddd aa ccc" o/p - aa,ccc,ddd,bbb Scala: ...
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2answers
94 views

List of Happy Numbers in scala

Definition of Happy numbers taken from Wikipedia. A happy number is defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits ...
2
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1answer
111 views

Game of Life with Scala and Functional Programming

I have been doing OOP and imperative programming my whole career but I wanted to dabble in Scala along with functional programming. Rather than writing Java like code in Scala I wanted to try a more ...
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1answer
251 views

Calculate simple arithmetic string in Scala

Problem Given an arithmetic string like 2+2*3 calculate result 8. Assumptions you can make string will be always well formed (no error checking needs to be done) only operators passed in string ...
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1answer
72 views

find if one string is a valid anagram of another , in scala

Question is taken from leet code. Problem Given two strings s and t , write a function to determine if t is an anagram of s. Examples ...
2
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1answer
276 views

Longest Substring Without Repeating Characters in Scala

Question is taken from Leetcode and solution works for their test cases. I do see a scope of improvement and make it more functional (getting rid of vars and mutables data structures). Please suggest ...
0
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1answer
38 views

Efficiency of grouping a List of case classes by more than one field

I have the following input: ...
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1answer
56 views

Check if list contains a pair which adds up to a given sum

Kindly review this scala code for given problem and suggest improvements. Problem - Given an array of integers and a target sum, check if array contains a pair which adds up to sum. Example - <...
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0answers
44 views

NQueen solution in scala

This is my solution for NQueen problem in scala. I just want to know how to make it more easy to read, modular and areas i need to improve. ...
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1answer
57 views

Find the combination of matches which are closest to each other

Problem - Given three sorted arrays find combinations which are closest to each other. example - ...
3
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1answer
71 views

Mark positions attacked by a queen on a chess board

Problem - Given a chess board and the position of only one queen piece in it, mark all the position where the queen can move with X. Kindly review this Scala code and suggest improvements. ...

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