CF268D.Wall Bars

普及/提高-

通过率:0%

AC君温馨提醒

该题目为【codeforces】题库的题目,您提交的代码将被提交至codeforces进行远程评测,并由ACGO抓取测评结果后进行展示。由于远程测评的测评机由其他平台提供,我们无法保证该服务的稳定性,若提交后无反应,请等待一段时间后再进行重试。

题目描述

Manao is working for a construction company. Recently, an order came to build wall bars in a children's park. Manao was commissioned to develop a plan of construction, which will enable the company to save the most money.

After reviewing the formal specifications for the wall bars, Manao discovered a number of controversial requirements and decided to treat them to the company's advantage. His resulting design can be described as follows:

  • Let's introduce some unit of length. The construction center is a pole of height nn .
  • At heights 1,2,...,n1,2,...,n exactly one horizontal bar sticks out from the pole. Each bar sticks in one of four pre-fixed directions.
  • A child can move from one bar to another if the distance between them does not exceed hh and they stick in the same direction. If a child is on the ground, he can climb onto any of the bars at height between 11 and hh . In Manao's construction a child should be able to reach at least one of the bars at heights nh+1,nh+2,...,nn-h+1,n-h+2,...,n if he begins at the ground.

The figure to the left shows what a common set of wall bars looks like. The figure to the right shows Manao's constructionManao is wondering how many distinct construction designs that satisfy his requirements exist. As this number can be rather large, print the remainder after dividing it by 1000000009 (109+9)1000000009 (10^{9}+9) . Two designs are considered distinct if there is such height ii , that the bars on the height ii in these designs don't stick out in the same direction.

输入格式

A single line contains two space-separated integers, nn and hh ( 1<=n<=10001<=n<=1000 , 1<=h<=min(n,30)1<=h<=min(n,30) ).

输出格式

In a single line print the remainder after dividing the number of designs by 1000000009 (109+9)1000000009 (10^{9}+9) .

输入输出样例

  • 输入#1

    5 1
    

    输出#1

    4
    
  • 输入#2

    4 2
    

    输出#2

    148
    
  • 输入#3

    4 3
    

    输出#3

    256
    
  • 输入#4

    5 2
    

    输出#4

    376
    

说明/提示

Consider several designs for h=2h=2 . A design with the first bar sticked out in direction d1d_{1} , the second — in direction d2d_{2} and so on ( 1<=di<=41<=d_{i}<=4 ) is denoted as string d1d_{1} d2d_{2} ...... dnd_{n} .

Design "1231" (the first three bars are sticked out in different directions, the last one — in the same as first). A child can reach neither the bar at height 3 nor the bar at height 4.

Design "414141". A child can reach the bar at height 5. To do this, he should first climb at the first bar, then at the third and then at the fifth one. He can also reach bar at height 6 by the route second fourth sixth bars.

Design "123333". The child can't reach the upper two bars.

Design "323323". The bar at height 6 can be reached by the following route: first third fourth sixth bars.

首页