Start by clarifying the problem and edge cases, then propose a backtracking solution that builds the string character by character, pruning branches that would create consecutive 1s. Discuss the time complexity and possible optimizations, such as using dynamic programming to count or generate strings efficiently.
Pro tip: Mention that the number of valid strings follows the Fibonacci sequence, which can impress the interviewer and lead to a discussion on using DP for counting or generating strings. Also, consider asking whether the output should be returned as a list or printed, and whether N can be zero.
Ask about input constraints (e.g., N >= 0), output format (list of strings, print, etc.), and whether the solution should be recursive or iterative. Confirm that 'no two consecutive 1s' means no substring '11'.
Explain that you can build the string position by position, tracking the last character. At each step, you can append '0' always, and append '1' only if the last character was not '1'. This prunes invalid branches early.
State that the number of valid strings is Fibonacci(N+2), so the time complexity is O(Fib(N)) which is exponential in N. Mention that for large N, generating all strings is infeasible, but for counting, DP can be used.
Mention that you could also use dynamic programming to count the number of valid strings, or generate them using a recursive function that returns a list of strings. Compare trade-offs.
Write clean code (e.g., in Python) with a recursive helper function. Test with small N (e.g., N=1,2,3) and edge cases like N=0.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.