How do I summarize array of integers as an array of ranges?

Question

I\'d like to take input such as:

[1,2,4,5,6,7,9,13]

and turn it into something like the following:

[[1,2],[4,7],[9,9],[13,1         


        

Answer 1

Another approach

def summarize(x)
  x.inject([]) do |acc, value|
    if acc.last && acc.last[1] + 1 == value
      acc.last[1] = value
      acc
    else
      acc << [value,value]
    end
  end
end

Similar to Larsenal's method but using inject to manage the boring stuff.