这是一个计算大数阶乘的算法． ** 主要是通过链表来保存结果的每一位数。 ** 这样就不会有像long或int类型时，数太大而导致溢出的情况-This is a calculation of factorial of large numbers of the algorithm.** Mainly through the list to save the results of each of the median.** So there will not be as long or in