题目：Problem
Description
Queues
and Priority Queues are data structures which are known to most computer
scientists. The Queue occurs often in our daily life. There are many people
lined up at the lunch time.
Now
we define that ‘f’ is short for female and ‘m’ is short for male. If the queue’s
length is L, then there are 2
L numbers of queues. For example,
if L = 2, then they are ff, mm, fm, mf . If there exists a subqueue as fmf or
fff, we call it O-queue else it is a E-queue.
Your task is to calculate the
number of E-queues mod M with length L by writing a program.
Input
Input
a length L (0 <= L <= 10 6) and M.
Output
Output
K mod M(1 <= M <= 30) where K is the number of E-queues with length
L.
Sample Input
Sample Output
Author
WhereIsHeroFrom
Source
题目数据不强，正解应该是要矩阵快速幕，但是这不是我要说的重点
重点是推导过程：
如果F[N-1]：最后一项是M的话，就有ANS+=F[N-1];
如果是是L的话结果就是：ANS+=F[N-3]+MM,ANS+=F[N-3]+MF,其他的不符合，
但是F[N-3]+mf要考虑发 f[n-4]不能是F的情况，比较绕；结论是：
F[N-1]+M+F[N-3]+MMF+F[N-4]+FMMF+MMMF;
HDU-2604_Queuing,布布扣,bubuko.com
HDU-2604_Queuing
原文：http://www.cnblogs.com/forgot93/p/3634919.html
