var iterations: Int = 0
fun main(args: Array<String>) {
    var list = listOf(1, 3, 5, 8, 12, 13, 22)
    list = list.sorted()

    println("enter the target number!")
    val target = readLine()!!.toInt()
    if (target % 2 == 1) println("No pair possible, number odd!")

    for (element in list){
        iterations++
        if (element > target) break
        val remaining = target - element
        if (binarySearch(list, remaining)) {
            println("Found pair = $element + $remaining = $target, $iterations iterations")
            return
        }
    }
    println("Couldn't find a pair, $iterations iterations")
}

// from geeksforgeeks.org
fun binarySearch(arr: List<Int>, x: Int): Boolean {
    var l = 0
    var r = arr.size - 1
    while (l <= r) {
        iterations++
        val m = l + (r - l) / 2

        // Check if x is present at mid
        if (arr[m] == x)
            return true

        // If x greater, ignore left half
        if (arr[m] < x)
            l = m + 1
        else
            r = m - 1// If x is smaller, ignore right half
    }

    // if we reach here, then element was
    // not present
    return false
}