Question

How to implement a cumulative sum of numbers in an int array in Scala

Answer 1

object CumulativeSumOfIntArray_Scala {
  def CumulativeSumOfIntArray(arr: Array[Int]): Array[Int] = {
    val sum_arr = new Array[Int](arr.length)
    var sum = 0
    
    for (i <- 0 until arr.length) {
      sum += arr(i)
      sum_arr(i) = sum
    }
    
    sum_arr
  }

  def main(args: Array[String]): Unit = {
    val arr = Array(0, 1, 2, 3, 4, 5, 6)
    
    val sum_arr = CumulativeSumOfIntArray(arr)
    
    for (n <- sum_arr) {
        print(s"$n ")
    }
  }
}



/*
run:

0 1 3 6 10 15 21 

*/

 

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Answer 2

object CumulativeSumOfIntArray_Scala {
  def main(args: Array[String]): Unit = {
    val arr =  Array(0, 1, 2, 3, 4, 5, 6)
    
    val cumulativeSum = arr.scanLeft(0)(_ + _).tail
    
    println(cumulativeSum.mkString(", "))
  }
}




/*
run:

0, 1, 3, 6, 10, 15, 21

*/

 

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