Given two positive integer strings low and high, return the number of stepping numbers in the inclusive range $[$low, high$]$. Since the answer may be large, return it modulo $10^9 + 7$.

A stepping number is an integer where the absolute difference between any two adjacent digits is exactly $1$. Every single digit number is also considered a stepping number.

Constraints:

• $1 \leq$ int(low) $\leq$ int(high) $< 10^{100}$

• $1 \leq$ low.length, high.length $\leq 100$

• low and high consist of only digits.

• low and high do not have any leading zeros.

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.