During my recent job search I was asked many questions I didn't know the secret algorithm to, but if those companies had given me the problem ahead of time and allowed me to research it -- just like what happens in real life -- I could have coded solutions to all of them.
And if you're worried about people just plagiarizing existing solutions, have them talk through it, as you say. Should be fairly clear if they understand each line or not.
During my recent job search I was asked many questions I didn't know the secret algorithm to, but if those companies had given me the problem ahead of time and allowed me to research it -- just like what happens in real life -- I could have coded solutions to all of them.
And if you're worried about people just plagiarizing existing solutions, have them talk through it, as you say. Should be fairly clear if they understand each line or not.