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Scala count for loop

Possible duplicate:
Reduction for loop in Scala?

While running Scala For Impatient, I came up with the following exercise:

Write a Scala equivalent for the Java loop
       for (int i = 10; i> = 0; i--) System.out.println (i);

It didn't take me long to come up with the following solution:

   for (i <- 1 to 10 reverse) {
       println(i)
   }

However, it made me think about how to reason about the cost of this. Does the inverse O (n) method go around the range, or does it decorate it with something that does fantastic index arithmetic? Are there other designs that can do this better?

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1 answer

You can always choose a step:

for (i <- 10 to 1 by -1) {
       println(i)
}

. , Range ( O (1)):

final override def reverse: Range =
    if (length > 0) new Range.Inclusive(last, start, -step)
    else this

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