TL;DR - I came up with an ingenious version of a solution to a problem and still got 0 marks.

In my bachelor's degree we learned about abstraction, as usual for CS degree students.

In a later exam, a coding question asked us to swap two variables values without using a third variable and print the before and after on the screen.

You can read the question above again, because wait for it....

So this is what I wrote basically (JS equivalent solution),

class Solution {
constructor(obj) {
this.var1 = obj.var1;
this.var2 = obj.var2;
}

swap() {
return {"var1": this.var2, "var2": this.var1};
}
}

let input = {"var1":5, "var2": 7}
let object = new Solution(input);
console.log('Before');
console.log(input);
let solution = object.swap();
console.log('After');
console.log(solution);

Now look, before your boomer asses jump in and say "aCkChUaLlY tHiS iS iNcORrEcT"
I did include all kinds of comments that this is abstracted. The swap function is hidden away and the object variable doesn't need to know what it's doing.

In the context of this question, this is absolutely acceptable as a solution since the end-goal is to print the results on the screen and the user wouldn't see the source code.

I still got 0 on that question and I still get pissed about it sometimes, when I remember it, like just now.