Archives functional programming - Page 2 of 3

Hackerrank – Rotate String

Problem Statement A description of the problem can be found on Hackerrank. Solution I created solution in: Scala All solutions are also available on my GitHub. Scala

object RotateString extends App {

   val lines = io.Source.stdin.getLines().toList
   val n = lines.head.toInt
   val strings = lines.tail

   strings.foreach(s =>
     println(rotations(s, 0).mkString(" "))
   )

   def rotate(s: String): String = {
     s.tail + s.head
   }

   def rotations(s: String, n: Int): List[String] = {
     if(n == s.length) Nil else rotate(s) :: rotations(rotate(s), n + 1)
   }
 }

object RotateString extends App {

val lines = io.Source.stdin.getLines().toList

val n = lines.head.toInt

val strings = lines.tail

strings.foreach(s =>

println(rotations(s, 0).mkString(" "))

)

def rotate(s: String): String = {

s.tail + s.head

}

def rotations(s: String, n: Int): List[String] = {

if(n == s.length) Nil else rotate(s) :: rotations(rotate(s), n + 1)

}

Hackerrank – Prefix Compression

Problem Statement A description of the problem can be found on Hackerrank. Solution Compare all characters from both string at the same index until they are not equals or we get to the end of one of strings. Equals characters are desired prefix. I created solution in: Scala All solutions are also available on my […]

Hackerrank – Evaluating e^x

Problem Statement A description of the problem can be found on Hackerrank. Solution

object EvaluatingEx extends App {
  def f(x: Double): Double =
    {
      f2(x, 9)
    }

  def fact(x: Int): Int = if (x <= 1) 1 else x * fact(x - 1)

  def f2(x: Double, i: Int): Double =
    {
      if (i == 0) 1 else Math.pow(x, i) / fact(i) + f2(x, i - 1)
    }

  val n = readInt
  (1 to n) foreach (x => println(f(readFloat())))
}

object EvaluatingEx extends App {

def f(x: Double): Double =

{

f2(x, 9)

}

def fact(x: Int): Int = if (x <= 1) 1 else x * fact(x - 1)

def f2(x: Double, i: Int): Double =

{

if (i == 0) 1 else Math.pow(x, i) / fact(i) + f2(x, i - 1)

}

val n = readInt

(1 to n) foreach (x => println(f(readFloat())))

}

Solution also available on my GitHub.

Hackerrank – Update List

Problem Statement A description of the problem can be found on Hackerrank. Solution

object UpdateList extends App {
  def f(arr: List[Int]): List[Int] = 
    if (arr.isEmpty) Nil else arr.head.abs :: f(arr.tail)
}

object UpdateList extends App {

def f(arr: List[Int]): List[Int] =

if (arr.isEmpty) Nil else arr.head.abs :: f(arr.tail)

}

Solution also available on my GitHub.

Hackerrank – List Length

Problem Statement A description of the problem can be found on Hackerrank. Solution

object ListLength extends App {

  def f(arr: List[Int]): Int = {
    var count = 0
    for (i <- arr) count += 1
    count
  }
  
  println(f(io.Source.stdin.getLines.toList.map(_.trim).map(_.toInt)))
}

object ListLength extends App {

def f(arr: List[Int]): Int = {

var count = 0

for (i <- arr) count += 1

count

}

println(f(io.Source.stdin.getLines.toList.map(_.trim).map(_.toInt)))

}

Solution also available on my GitHub.

Hackerrank – Sum of odd elements

Problem Statement A description of the problem can be found on Hackerrank. Solution

object SumOddElements extends App{
   def f(arr:List[Int]):Int = arr.filter(_ % 2 != 0).sum
}

object SumOddElements extends App{

def f(arr:List[Int]):Int = arr.filter(_ % 2 != 0).sum

}

Solution also available on my GitHub.

Hackerrank – Reverse a list

Problem Statement A description of the problem can be found on Hackerrank. Solution

object ReverseList extends App {
  def f(arr: List[Int]): List[Int] =
    (arr.foldLeft(List.empty[Int])((list, e) => e :: list))
}

object ReverseList extends App {

def f(arr: List[Int]): List[Int] =

(arr.foldLeft(List.empty[Int])((list, e) => e :: list))

}

Solution also available on my GitHub.

Hackerrank – Array Of N Elements

Problem Statement A description of the problem can be found on Hackerrank. Solution

object ArrayOfN extends App {

  def f(num: Int): List[Int] = (1 to num).toList

  println(f(readInt).length)

}

object ArrayOfN extends App {

def f(num: Int): List[Int] = (1 to num).toList

println(f(readInt).length)

}

Solution also available on my GitHub.

Hackerrank – Filter positions in a list

Problem Statement A description of the problem can be found on Hackerrank. Solution

object FilterPositions extends App {
  def f(arr: List[Int]): List[Int] =
    arr match {
      case x :: y :: l => y :: f(l)
      case x :: y => y
      case Nil => Nil
    }

  println(f(io.Source.stdin.getLines.toList.map(_.trim).map(_.toInt)).mkString("\n"))
}

object FilterPositions extends App {

def f(arr: List[Int]): List[Int] =

arr match {

case x :: y :: l => y :: f(l)

case x :: y => y

case Nil => Nil

}

println(f(io.Source.stdin.getLines.toList.map(_.trim).map(_.toInt)).mkString("\n"))

}

Solution also available on my GitHub.

Hackerrank – Filter Array

Problem Statement A description of the problem can be found on Hackerrank. Solution

object FilterArray extends App {

  def f(num: Int, arr: List[Int]): List[Int] = arr.filter(_ < num)

  var lines = io.Source.stdin.getLines.toList
  println(f(lines(0).toInt, lines.map(_.trim).map(_.toInt)).map(_.toString).mkString("\n"))

}

object FilterArray extends App {

def f(num: Int, arr: List[Int]): List[Int] = arr.filter(_ < num)

var lines = io.Source.stdin.getLines.toList

println(f(lines(0).toInt, lines.map(_.trim).map(_.toInt)).map(_.toString).mkString("\n"))

}

Solution also available on my GitHub.

Pavol Pidanič

I can count to 1023 with 10 fingers

Tag: functional programming

Hackerrank – Rotate String

Hackerrank – Prefix Compression

Hackerrank – Evaluating e^x

Hackerrank – Update List

Hackerrank – List Length

Hackerrank – Sum of odd elements

Hackerrank – Reverse a list

Hackerrank – Array Of N Elements

Hackerrank – Filter positions in a list

Hackerrank – Filter Array