Given a $0$ indexed integer array nums of length $n$ containing a permutation of numbers from $1$ to $n$, return the number of quadruplets (i, j, k, l) such that:

$0 \leq$ i < j < k < l < $n$ and nums[i] < nums[k] < nums[j] < nums[l].

Constraints:

• $4 \leq$ nums.length $\leq 4000$

• $1 \leq$ nums[i] $\leq$ nums.length

• All the integers of nums are unique. nums is a permutation.

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.