How would you display an array of integers as a set of ranges? (algorithm)

Question

Given an array of integers, what is the simplest way to iterate over it and figure out all the ranges it covers? for example, for an array such as:

$numbers = ar         


        

Answer 1

Assuming the list is ordered you could start at the end and keep subtracting the next one down. While the difference is 1, you're in a range. When it's not, you start a new range.

i.e

16-15 = 1

15-14 = 1

14-12 = 2, the range is 16-14 - start a new range.