P9651 [SNCPC2019] Digit Product
Description
Define the ''digit product'' $f(x)$ of a positive integer $x$ as the product of all its digits. For example, $f(1234) = 1 \times 2 \times 3 \times 4 = 24$, and $f(100) = 1 \times 0 \times 0 = 0$.
Given two integers $l$ and $r$, please calculate the following value:
$$(\prod_{i=l}^r f(i)) \mod (10^9+7)$$
In case that you don't know what $\prod$ represents, the above expression is the same as
$$(f(l) \times f(l+1) \times \dots \times f(r)) \mod (10^9+7)$$
Input Format
N/A
Output Format
N/A
Explanation/Hint
For the first sample test case, the answer is $9! \mod (10^9+7) = 362880$.
For the second sample test case, the answer is $(f(97) \times f(98) \times f(99)) \mod (10^9+7) = (9 \times 7 \times 9 \times 8 \times 9 \times 9) \mod (10^9+7) = 367416$.