单项链表和双向环链表

thisfileisthetestofthesinglelinked-listanddoublelinked-listtakecarethateachnodeinthelisthaveakeyid,thenodewithsamekeyidcanonlybeaddedonce,beforeonenodeisadded,theroutinewillcheckiftherehavethenodethathavethesamekeyid,ifthelisthave,routinewilldeleltethepreviousnode,andthen