title: Function on an array of real numbers that finds out if number in the array is composed for every number in array
body: <p>We have a set/array M of real numbers. A number r in M is composed if there are s and t in M with
  r = s + t.
  The goal is to find an algorithm (in pseudocode) that runs in O(n^2), that decides for every r in M if the r is composed or not. The array is sorted in ascending order.</p>
  <p>I have no clue how to find a algorithm in given time complexity.
  Thanks in advance for every input given</p>