Working at FB, +1 to all of this. Personally I find that I can get a lot more useful signal from simple practical problems (eg "take a .txt file as input, modi

Working at FB, +1 to all of this. Personally I find that I can get a lot more useful signal from simple practical problems (eg "take a .txt file as input, modify all the words which contain the letter 'q' to be uppercase, write the results to a new file") which have a lot of room for expansion (What if we instead want to capitalise each word where the word after it contains a 'q'? What if we only want to modify the third instance of each word? What if the .txt file is too large for RAM? What if a single 'word' is too large for ram and the letter q is right at the end of the word?) -- starting out with something that any programmer should be able to solve in one or two minutes, and then cranking up the difficulty; adding in bits where a strong algorithmic coder has an opportunity to come up with a more efficient solution, but it isn't just a binary "has the candidate memorised the appropriate algorithm yes/no?". (Example question made up off the top of my head because NDA, I haven't actually given much throught as to if it's a good question or not, just giving an example of "question which starts simple and then you can add complexity on top")