You are given an array of non negative integers nums.

Let rev(x) be a function that reverses the digits of a non negative integer x. For example, rev($123$) $=$ $321$, and rev($120$) $=$ $21$.

A pair of indices (i, j) is considered nice if:

• $0 \leq$ i $<$ j $<$ nums.length

• nums[i] $+$ rev(nums[j]) $=$ nums[j] $+$ rev(nums[i])

Return the total number of nice pairs. Since the answer may be very large, return it modulo $10^9 + 7$.

Constraints:

• $1 \leq$ nums.length $\leq 10^5$

• $0 \leq$ nums[i] $\leq 10^9$

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.