Do you have an example which correctly solves the problem but takes too long?

Behold

  var AGESORT = rows.bubblesort("AGE ASCENDING")
  var AGESORT1 = rows.bubblesort("AGE DESCENDING")
  var MALE = "None"
  var MALE1 = "None"

  for row in AGESORT
    if row.isMale
       MALE = row
       break

  for row in AGESORT1
    if row.isMale
      MALE1 = row
      break
    
  
  print "Min age: " + MALE
  print "Max age: " + MALE1

Stuff like this is usually the result of thoughts like "Ok, I'll break this problem into two, then combine the pieces. First I'll find the minimum age, which is easy once I sort the rows. Done. Ok, now I can see I can slightly alter that code so that it finds the max age! Now, I just put the pieces of code together, and do a little code organization to put like with like. I"

Good point.

Which problem? The first one? Don't underestimate the badness of the average interviewee.

For the "find the min and max of a set" in particular, a lot of folks start out with terrible solutions.

Well either I suppose. For the subset problem as you say a filter critera can be applied while looping through the collection. And that should be it. Now if the question was multiple criteria I could see the solution diverging rapidly. If the filter can be expressed as a rank we could sort the collection first and then binary search through it to find the boundaries. I suppose I'm just trying to imagine some way an interviewee may turn that into two loops, or three loops... more?