/*
Demonstration of traversing an array from both ends
at the same time in idiomatic Scala.
We use the classic "two‑index" technique:
- left starts at index 0
- right starts at index arr.length - 1
Both move toward the center.
This approach is efficient (O(n)), simple, and widely used in
algorithms such as palindrome checks, partitioning, and pair searching.
*/
// ------------------------------------------------------------
// Function: traverseFromBothSides
// Purpose: Traverse an array from both ends simultaneously.
// ------------------------------------------------------------
def traverseFromBothSides(arr: Array[Int]): Unit = {
var left: Int = 0 // left index
var right: Int = arr.length - 1 // right index
// Move inward until the indices cross
while (left <= right) {
println(s"Left: ${arr(left)}, Right: ${arr(right)}")
left += 1
right -= 1
}
}
// ------------------------------------------------------------
// Main program
// ------------------------------------------------------------
object TraverseBothEnds extends App {
val array: Array[Int] =
Array(10, 20, 30, 40, 50, 60, 70, 80, 90)
println("Traversing from both sides:")
traverseFromBothSides(array)
}
/*
run:
Traversing from both sides:
Left: 10, Right: 90
Left: 20, Right: 80
Left: 30, Right: 70
Left: 40, Right: 60
Left: 50, Right: 50
*/
