varabsences=[0,2,0,4,0,3,1,0]letmidpoint=absences.count/2varfirstHalf=absences.prefix(upTo:midpoint)letsecondHalf=absences.suffix(from:midpoint)来自苹果的引述:NeitherthefirstHalfnorsecondHalfslicesallocateanynewstorageoftheirown.Instead,eachpresentsaviewontothestorageoftheabsencesarray.当我尝试按如下方式改变first