| Re-implementing bubble-sort is, I think, a pretty reasonable fizzbuzz-style question. Can people think in loops. Depth first search I would now be a little less eager to do (I was asking these questions ten years ago), but there were a few things that I felt came out well from it: if someone wrote something like: if (DFS(node.left) || DFS(node.right)) return true else return false That seems to me like it demonstrates at the very least some immaturity of how to write professional code. If the person doesn't know how to do recursion, that stands out. If they fundamentally don't know how to deal with a stack, that stands out. If someone has never encountered DFS and just gets fundamentally stock on what the algorithm is at all, then that's, I agree, not wildly meaningful. But that was not, in general, a reason why people didn't get the DFS question. EDIT: I will also note that I've had a couple of people on HN react with horror at the notion that someone might be asked to impelement DFS or BFS. While I agree that these aren't perfect questions, I think they're pretty radically different than some of the puzzle-y or impossible-to-re-derive questions that you sometimes hear about. The algorithm for DFS is: 1. Check to see if the input is null. If it is, return false.
2. Check to see if the input's value is the searched operand. If it is, return true.
3. Return DFS(left) || DFS(right) Breadth-first is a tiny bit harder, but it's still a while loop on a queue and just test equality and push the children onto the queue. It's about ten lines of code and it's far from rocket science. If nobody ever taught you about binary trees at all, you might still be a great programmer. But if you're a good programmer, and you ever got taught about binary trees (which most people who have traditional backgrounds have), then you should be able to recreate those algorithms from first principles in, I don't know, 15-30 minutes. |