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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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
23 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
67 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
70 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 ...
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2k views

Adding columns in Spark dataframe based on rules

I have a dataframe df, which contains below data: ...
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2answers
60 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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1answer
47 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
42 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
60 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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1answer
75 views

Readable unit test - lists of complex objects

Goal: Writing more readable tests. I have a couple of functions, which basically merge and converts two lists of Datasets together, written using Scala and Spark. Each of these Datasets has a lot of ...
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1answer
52 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 - ...
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1answer
116 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 ...
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1answer
211 views

Run two computations in parallel, and return the results together

I am reading the "Learning Concurrent Programming in Scala" and there are exercises in the end of each chapter. One of exercises is Implement a parallel method which takes two computation blocks a ...
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3answers
121 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 ...
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1answer
533 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
35 views

Page download with reattempts in Scala

I wrote the following code to deal with possible network problems. ...
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2answers
65 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
42 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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1answer
72 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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50 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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2answers
59 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
75 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
40 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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0answers
46 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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1answer
76 views

Clockwise rotate a matrix in Scala

Given a matrix, clockwise rotate elements in it. Examples: ...
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1answer
60 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
103 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
420 views

Heap Sort in Scala

Trying to implement Heap Sort in Scala ...
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3answers
1k views

Connecting to RabbitMQ

I would like a review for this connection to RabbitMQ. I just developed it and seems to be working well, but I would like another set of eyes on it before putting this on the sever. ...
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2answers
54 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 ...
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29 views
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69 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
101 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
243 views

Functional K-way merge (Merge k sorted sequences)

I've implemented a functional k way-merge algorithm to merge k sorted sequences of any type T. I used scalaz's Heap since the Scala standard library does not provide an immutable heap. Any suggestions ...
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1answer
49 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 ...
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1answer
54 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
41 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
62 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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2answers
58 views

Project Euler - multiples of numbers

I'm trying to learn functional programming and Scala, following through Project Euler problems. I'm solving get the sum of multiples x & y in a list. So for a list ...
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1answer
70 views

Longest Collatz sequence in Scala

I am trying to find the longest Collatz Sequence: Which starting number, ≤ N, produces the longest chain? If many possible such numbers are there print the maximum one. (1 ≤ N ≤ 5×106) I tried ...
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1answer
759 views

Determining the HTTP status code to return for a request

I have a piece of code that I would like to refactor but can't figure how to do it. This is a method from a Play controller where I have to verify many precondition and respond different status for ...
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0answers
518 views

Scalaz state monad exercise to model sampling of coloured balls

Here is a self imposed exercise and solution to learn Scalaz state monad. How can I refactor it to take it to the next level? So far I've only studied the state monad so would welcome suggestions on ...
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1answer
63 views

Count lines of scala code (omitting empty lines) in a directory, traversing any subdirectories

I need to simply count lines of Scala code in a project, which includes some package(i.e. directory) hierarchy. I'm not sure about the performance of the code below. Can you help improve it, if ...
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1answer
97 views

Finding the number of inversions in an Array

I am doing a college assignment where I have to count the number of inversions in an array/list. An inversion is defined as a tuple where i<j and a[i]>a[j]. ...
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0answers
117 views

Add an attribute to specific XML Elements in Scala

supposed I have an XML like ...
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1answer
141 views

Binary search in Scala

Another exercise in Scala in which the goal is to find the target position as fast as possible. The initial input provides the grid size and the initial position. Each turn, this code provide a new ...
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1answer
114 views

Find an ideal speed to cross all traffic lights when they are green

As a second exercise with Scala I tried to solve another puzzle. In this puzzle, we have to find the highest speed that allows a driver to cross all the traffic lights when they are green, without ...
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1answer
63 views

Finding the nearest defibrillator exercise from CodingGames

For my first attempt at Scala I decided to solve a simple exercise on codingame.com. Based on a string input containing the user location, the defibrillators count and a list of defibrillators ...