HDOJ_ACM_Queuing

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

3 8
4 7
4 8

 

Sample Output

6
2
1

 

Code

Accepted-----

Wrong--------

Explanition

The reason why it is f(n)=f(n-1)+f(n-3)+f(n-4)

last letter

e:
　　e  -----------f(n-1)
f:
　　eef ----------f(n-3)
　　fef -----------0
　　fff  -----------0
eff:
　　feff ----------0
　　eeff-----------f(n-4)

Key Point

you must initialize the array every time!