The Question:
You are given a 0-indexed integer array nums.
The distinct count of a subarray of nums is defined as:
Let nums[i..j] be a subarray of nums consisting of all the indices from i to j such that 0 <= i <= j < nums.length. Then the number of distinct values in nums[i..j]is called the distinct count of nums[i..j].
Return the sum of the squares of distinct counts of all subarrays of nums.
A subarray is a contiguous non-empty sequence of elements within an array.
This is the solution online since I wasn’t able to solve it myself but I don’t understand how it takes all the subarrays into consideration:
Solution: