Sure, but without knowing what the grading criteria are (coding speed?, optimality of solution?, etc.) I can only go by what appears to be the criteria accordin

Sure, but without knowing what the grading criteria are (coding speed?, optimality of solution?, etc.) I can only go by what appears to be the criteria according to the signals I get during the interview ("Is there a more optimal solution?", "This looks good to me.", ...). And yes it is pass/fail often times.