A recent interview question that I had to review was spelled like this:
Find missing int element into array 1..100
Of course at first read I got it wrong, you have only one integer to look
for into the array. So while the obvious idea was to apply classic sorting
techniques and minimize array traversal to handle complexity (time and
space), it turns out there’s a much simpler way to do it if you remember
your math lessons from younger. But is it that much simpler?