Scala - 计算交错数组总和的惯用方法？

def calculateSum(arr: Array[Array[Int]]): Int = {
  val n = arr.length
  val dp = Array.ofDim[Int](n, n)

  dp(0)(0) = arr(0)(0)

  for (i <- 1 until n) {
    dp(i)(0) = dp(i-1)(0) + arr(i)(0)
    dp(i)(i) = dp(i-1)(i-1) + arr(i)(i)
  }

  for (i <- 2 until n) {
    for (j <- 1 until i) {
      dp(i)(j) = arr(i)(j) + Math.max(dp(i-1)(j-1), dp(i-1)(j))
    }
  }

  dp(n-1).max
}

val arr = Array(
  Array(2),
  Array(3, 4),
  Array(6, 5, 7),
  Array(4, 1, 8, 3)
)

val result = calculateSum(arr)
println(result)