> In the real world, you use a well-tested premade off the shelf library to traverse a DAG or implement a red/black tree. I reject your real world assertion, u

> In the real world, you use a well-tested premade off the shelf library to traverse a DAG or implement a red/black tree. I reject your real world assertion, unless you do not count Google as the real world. The reason these questions are asked is that they're relevant to the work engineers will be doing at Google.