Leetcode 2519. Count the Number of K-Big Indices

Given an integer array and k, count indices i such that the element at i is "k-big" — i.e., there are at least k elements greater than nums[i] on both its left and its right. Solving this efficiently requires prefix/suffix order-statistics (coordinate compression + Fenwick/segment tree or balanced BST) to compute those counts in O(n log n).