Area Under Curves and Volume of Revolving a Curve Discussions | Functional Programming | HackerRank
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  2. Functional Programming
  3. Introduction
  4. Area Under Curves and Volume of Revolving a Curve
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Area Under Curves and Volume of Revolving a Curve

  • franekfm
     + 0 comments

    scala:

      private val dx = 0.001
  def readLine() = scala.io.StdIn.readLine()

  def f(coefficients: Seq[Int], powers: Seq[Int], x: Double) = {
    (coefficients zip powers)
      .map { case (a, b) => a * math.pow(x, b) }
      .sum
  }

  def area(coefficients: Seq[Int], powers: Seq[Int], x: Double): Double = {
    Math.PI * Math.pow(f(coefficients, powers, x), 2)
  }

  def summation(
      func: (Seq[Int], Seq[Int], Double) => Double,
      upperLimit: Int,
      lowerLimit: Int,
      coefficients: Seq[Int],
      powers: Seq[Int]
  ): Double = {
    val steps = ((upperLimit - lowerLimit) / dx).toInt
    val range = (0 to steps).map(lowerLimit + _ * dx)
    val result = range
      .map(func(coefficients, powers, _) * dx)
      .sum
    BigDecimal(result).setScale(1, BigDecimal.RoundingMode.UP).toDouble
  }