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 = array(1,3,4,5,6,8,11,12,14,15,16); 

The ranges would be:

 1,3-6,8,11-12,14-16 

Answer 1

If the array is sorted in ascending order, then the problem is easy. Define a Range structure or class, which has a beginning and an end. Then go through the array. If the current element is one more than the previous, update Range.end, otherwise create a new range with this element as Range.begin. Store the ranges to a dynamic array or a linked list. Or just print them out as you go.

If the array may not be sorted, then sort it first.