They didn't mean "prove" as in mathematically "prove" than an algorithm works, they meant it in mechanical terms (does it compile, does it run, does it past test inputs, etc.).
That is not a proof by the CS standard though -- well, unless the job is defined as "write a program that processes these N test inputs known in advance", in which case a program that prints the expected hardcoded output in response to each of the expected inputs and otherwise returns an error would be a good implementation :)
I personally avoid using a word "proof" to mean anything other than a mathematical proof. It can be done with code, for sure, but as grandparent said, usually isn't.
I personally avoid using a word "proof" to mean anything other than a mathematical proof. It can be done with code, for sure, but as grandparent said, usually isn't.