Problem M
Deterministic Finite Automata - Enumeration
Languages
en
is
You are given a deterministic finite automaton that accepts the language $\mathcal{L}$. You will then be given queries asking for the number of words in $\mathcal{L}$ with a specified length, which you should answer in the order they are given.
Input
The input contains the description of a deterministic finite automaton.
The first line contains four positive integers $n$, $c$, $s$, and $f$, where $n$ is the number of states, $c$ is the size of the alphabet, $s$ is the initial state, and $f$ is the number of final states. The second line consists of a string $\Sigma = \Sigma _1\Sigma _2\dots \Sigma _c$ of $c$ distinct symbols, each of which is a lowercase english character. The third line consists of $f$ distinct positive integers, the set of final states. Then $n$ lines follow, each with $c$ positive integers, describing the symbol table. The $j$-th integer on the $i$-th of those lines represents the state transitioned to from state $i$ upon reading $\Sigma _j$.
Each state is an integer between $1$ and $n$. It is guaranteed that $1 \leq n \leq 2\, 000$, $1 \leq s \leq n$, and $0 \leq f \leq n$.
Finally, the input will contain an integer $m$ and then $m$ lines. The $i$-th line will contain $\ell _i$, for $1 \leq i \leq m$, querying for the number of words with length $\ell _i$ in $\mathcal{L}$. You may assume that $\ell _i \cdot n \leq 500\, 000$ for each $i$.
Output
For each of the $m$ queries, output the number of words with the specified length in $\mathcal{L}$. As these numbers can be quite large, output them modulo $1\, 000\, 000\, 007$.
Sample Input 1 | Sample Output 1 |
---|---|
5 2 1 2 ab 4 5 2 3 3 4 4 5 5 4 4 4 5 0 1 2 3 4 |
0 0 3 8 16 |
Sample Input 2 | Sample Output 2 |
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2 4 1 1 acgt 1 2 2 2 2 2 2 2 2 3 0 1 2 |
1 0 0 |