Introduction - If you have any usage issues, please Google them yourself
Algorithm analysis: the entire string in turn write back the original string. The middle separated by a special character, the middle I use 0, the last face I added a character one, if there is likely to be wrong 0. (The last one should also not), so put the problem into a request string of a new two longest common prefix suffix NOTE: to provide the answer should be a set of data zzzdzaadzzz output zzz, and if not careful, then procedures may enter zdz, because there may be no answer to the prefix is adjacent to the loop where a judge had to deal with. WA three times because of this