Water collected between towers

Question

I recently came across an interview question asked by Amazon and I am not able to find an optimized algorithm to solve this question:

You are given an input array wh

Answer 1

Here is one more solution written on Scala

def find(a: Array[Int]): Int = {
  var count, left, right = 0

  while (left < a.length - 1) {
    right = a.length - 1
    for (j <- a.length - 1 until left by -1) {
      if (a(j) > a(right)) right = j
    }

    if (right - left > 1) {
      for (k <- left + 1 until right) count += math.min(a(left), a(right)) - a(k)
      left = right
    } else left += 1
  }

  count
}