There are at least 2 ACTUAL solutions, which don’t involve beating someone with the seesaw nor prototyping a digital weight scale nor asking the 12 computer scientists to brainstorm with you.
Hint #2: Think about the base case, which means, if you can only use the seesaw once, under what conditions (how many candidates, etc) can you identify the one with different weight.
Hint #3: The first step should be dividing 12 computer scientists into 3 groups of 4 people.
There are 10 sets of 10 computer scientists. 9 sets of them are weight exactly the same, and you already know how much weight they should be. However, in the last set of computer scientests, all of them are 1 kg off (you have no idea they are either all 1 kg ligher or all 1 kg heavier), making the entire set of computer scientists 10 kg lighter or heavier than the other sets.
There are 12 computer scientists, 11 of them have the exact same weight. However, the last one is either heavier or lighter than others (but you don’t know which is the case).