Cisco Logic Design Engineer interview questions

You need to design a logic system with input of a stream of bits and it needs to detect a known chunk of bits, e.g. '1000'. First, implement a naive system. What are the inputs and outputs? Which logic gates, modules and blocks do you need? Analyze it with respect to timing, efficiency, hardware usage, etc. Second, try to come up with a more efficient implementation. Analyze it again. Compare the two implementations.