You are right, these questions are generally a terribly signal towards your capabilities or intelligence. They require a disproportionate amount of effort on your part. Now that we got the complaining out of the way, if you are interested in getting jobs in this industry, I'd recommend practicing implementations of these standard questions in your favorite language and just saving them somewhere to review occasionally. There's a pattern to most of the questions and they usually tend to fall on figuring out an algorithmic trick or using a special data structure. It's ridiculous how many things are solvable in an efficient manner with a hash table...in a contrived interview question that is ;)