说明：  试写一算法,实现顺序表的就地逆置,即利用原表的存储空间将线性表(a1,a2,...,an)逆置为(an,an-1,...,a1).
(try to write an algorithm to achieve the order form in situ reverse home, namely the use of the original table of linear storage space (a1, a2 ,..., an) inverse home (an, an-1 ,..., a1).)