2921. Corn Fields

单点时限: 2.0 sec

内存限制: 256 MB

Farmer John has purchased a lush new rectangular pasture composed of by square parcels. He wants to grow some yummy corn for the cows on a number of squares. Regrettably, some of the squares are infertile and can’t be planted. Canny FJ knows that the cows dislike eating close to each other, so when choosing which squares to plant, he avoids choosing squares that are adjacent; no two chosen squares share an edge. He has not yet made the final choice as to which squares to plant.

Being a very open-minded man, Farmer John wants to consider all possible options for how to choose the squares for planting. He is so open-minded that he considers choosing no squares as a valid option! Please help Farmer John determine the number of ways he can choose the squares to plant.

输入格式

Line : Two space-separated integers: and
Lines .. : Line describes row of the pasture with space-separated integers indicating whether a square is fertile ( for fertile, for infertile)

输出格式

One integer: the number of ways that FJ can choose the squares modulo .

样例

Input
2 3
1 1 1
0 1 0
Output
9

提示

Number the squares as follows:

1 2 3
  4

There are four ways to plant only on one squares (1, 2, 3, or 4), three ways to plant on two squares (13, 14, or 34), 1 way to plant on three squares (134), and one way to plant on no squares. 4+3+1+1=9.

4 人解决,12 人已尝试。

9 份提交通过,共有 34 份提交。

8.5 EMB 奖励。

创建: 8 年,6 月前.

修改: 2 年,3 月前.

最后提交: 1 年,3 月前.

来源: USACO 2006 November Gold

题目标签
DP