Frankly, I find this type of interview insulting. Let's face it. Unless you work with "algorithms" on a dialy basis, I'm willing to bet that most who do not cannot regurgitate a red black tree at the drop of a hat. I work in this field off in on as an embedded developer and I'm always going to various texts on the subject to align my thinking with the code I'm writing (C++ in my case). It's one thing to talk through these scenarios in an interview and it's yet another to judge one's ability to solve problems on how well they come up with a solution to an interview question. I give merit to the "talking through" and this is what I do. I find that if a candidate can carry on an intelligent conversation about a particular problem domain, he's hirable material and in 15 years of running my own company I've had only 2 out of 43 people leave my company.