2913. Subarrays Distinct Element Sum of Squares I

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.

class Solution {
public:
    int sumCounts(vector<int>& nums) {
        int res = 0;
        for(int i = 0; i < nums.size(); i++) {
            unordered_set<int> us;
            int sum = 0;
            for(int j = i; j < nums.size(); j++) {
                us.insert(nums[j]);
                res += us.size() * us.size();
            }
        }
        return res;
    }
};