We may be mishearing their intended formulation, which could have been asking for the longest common substring (described here: difference is that subsequences

We may be mishearing their intended formulation, which could have been asking for the longest common substring (described here: difference is that subsequences don't have to be entirely contiguous, just in the same order.) http://en.wikipedia.org/wiki/Longest_common_substring_problem http://en.wikipedia.org/wiki/Longest_common_substring_proble... That's an interesting problem with some simple solutions worth understanding. I don't think it would be unrealistic to expect a high-quality programmer to be previously familiar with it, or, if not previously familiar, to be able to make progress toward the DP solution with some thought.