Leetcode 2857. Count Pairs of Points With Distance k

Count unordered pairs of points (i<j) whose distance defined as (xi XOR xj) + (yi XOR yj) equals k; with n up to 50k and k ≤ 100, the challenge is to avoid O(n^2) by using frequency maps and combining counts of possible XOR contributions (0..k) for x and y.