2465. Number of Distinct Averages

You are given a 0-indexed integer array nums of even length.

As long as nums is not empty, you must repetitively:

• Find the minimum number in nums and remove it.
• Find the maximum number in nums and remove it.
• Calculate the average of the two removed numbers.

The average of two numbers a and b is (a + b) / 2.

• For example, the average of 2 and 3 is (2 + 3) / 2 = 2.5.

Return the number of distinct averages calculated using the above process.

Note that when there is a tie for a minimum or maximum number, any can be removed.

class Solution {
public:
    int distinctAverages(vector<int>& nums) {
        unordered_set<int> us;
        sort(begin(nums),end(nums));
        int l = 0, r = nums.size() - 1;
        while(l < r) {
            us.insert(nums[l] + nums[r]);
            l += 1;
            r -= 1;
        }
        return us.size();
    }
};