Problem B. Rikka with String
时间限制 3000 ms
内存限制 64 MB
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 $n$ $01$ strings $s_i$, and he wants to know the number of $01$ antisymmetric strings of length $2L$ which contain all given strings $s_i$ as continuous substrings.
A $01$ string $s$ is antisymmetric if and only if $s[i] \neq s[|s|-i+1]$ for all $i \in [1,|s|]$.
It is too difficult for Rikka. Can you help her?
In the second sample, the strings which satisfy all the restrictions are $000111,001011,011001,100110$.
输入数据
输出数据
For each testcase, print a single line with a single number -- the answer modulo 998244353.
样例输入
复制
2
2 2
011
001
2 3
011
001
样例输出
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