This was extremely weird: There is an algorithm with the runtime O(n^2 log(n)). It generates all possible pairs. Then he asked me "Whats the name of this algorithm?". What he meant was "Whats the name of the strategy of this algorithm?" or "How is this algorithm operating?" ==> Divide & Conquer was the answer. Then I had to code it. In reality super simple but asking it this way made it a lot harder...