objectMainextendsApp{ varreverse_pairs = 0//逆序數 defmsort[T](cmp:(T, T) => Boolean)(l:List[T]):List[T] = { defmerge(l1:List[T], l2:List[T]):List[T]=(l1, l2)match{ case(Nil, _) => l2 case(_, Nil) => l1 case(x::left1, y::left2) => if(cmp(x, y)) x::merge(left1, l2) else{ reverse_pairs += l1.length y::merge(l1, left2) } } valn = l.length / 2 if(n == 0) return l else{ val(l1, l2) = l.splitAt(n) merge(msort(cmp)(l1), msort(cmp)(l2)) } } println(msort((x:Int, y:Int) => x<y)(List(5, 4, 3, 2, 7,6 ))) println(reverse_pairs)