// bubble sort demo program

println("how many integers?")
val N = readInt

println("do you want to print the data before/after?  ('y' for yes)")
val input = readLine
val verbose = (input == "y")

val nums = Array.fill(N)(util.Random.nextInt(100))

if (verbose) {
  println("before:")
  nums.foreach(println(_))
}

bubblesort(nums)

if (verbose) {
  println("after:")
  nums.foreach(println(_))
}

if (isSorted(nums)) {
  println("success!")
}
else {
  println("the programmer messed up!")
}

def bubblesort(nums : Array[Int]) = {

  for (endIndex <- nums.size -1 to 1 by -1) {
    for (i <- 0 until endIndex) {
      // compare nums(i) with nums(i+1) and exchange if needed
      if (nums(i) > nums(i+1)) {
        val tmp = nums(i)
        nums(i) = nums(i+1)
        nums(i+1) = tmp
      }
    }
  }
}

def isSorted(nums : Array[Int]) : Boolean  = {
  var result = true
  for (i <- 0 until nums.size-1) {
    if (nums(i) > nums(i+1)) 
      result = false
  }
  result
}