ACM-ICPC-OJ训练营

问题 1834 --Rikka with String

1834: Rikka with String

时间限制: 6 Sec 内存限制: 128 MB
提交: 1 解决: 1
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题目描述

As we know, Rikka is poor at math. Yuta is worrying about this situation, so he gives Rikka some math tasks to practice. There is one of them:
Yuta has

01 strings

si, and he wants to know the number of

01 antisymmetric strings of length

2L which contain all given strings

si as continuous substrings.
A

01 string

s is antisymmetric if and only if

s[i]≠s[|s|−i+1] for all

i∈[1,|s|].
It is too difficult for Rikka. Can you help her?
In the second sample, the strings which satisfy all the restrictions are

000111,001011,011001,100110.

输入描述

The first line contains a number

t(1≤t≤5), the number of the testcases.

For each testcase, the first line contains two numbers

n,L(1≤n≤6,1≤L≤100).

Then

n lines follow, each line contains a

01 string

si(1≤|si|≤20).

输出描述

For each testcase, print a single line with a single number -- the answer modulo 998244353.

样例输入

样例输出

1
4

来源

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