1644.
Function
时间限制 2000 ms
内存限制 128 MB
You are given a permutation $a$ from $0$ to $n - 1$ and a permutation $b$ from $0$ to $m - 1$.
Define that the domain of function $f$ is the set of integers from $0$ to $n - 1$, and the range of it is the set of integers from $0$ to $m - 1$.
Please calculate the quantity of different functions $f$ satisfying that $\displaystyle f(i) = b_{f(a_i)}$ for each $i$ from $0$ to $n - 1$.
Two functions are different if and only if there exists at least one integer from $0$ to $n - 1$ mapped into different integers in these two functions.
The answer may be too large, so please output it in modulo $10^9 + 7$.
输入数据
输出数据
For each test case, output "Case #$x$: $y$" in one line (without quotes), where $x$ indicates the case number starting from $1$ and $y$ denotes the answer of corresponding case.
样例输入
复制
3 2
1 0 2
0 1
3 4
2 0 1
0 2 3 1
· \n
· · \n
· \n
· \n
· · \n
· · · \n
样例输出
复制
Case #1: 4
Case #2: 4
· · \n
· · \n