Rearrange array to maximize positive prefix sums

## Problem You are given an integer array `a` of length `n`. You may **rearrange** the elements in any order. Define the prefix sums of a permutation `p` as: - `pref[i] = p[0] + p[1] + ... + p[i]` for `0 <= i < n` Let `score(p)` be the number of indices `i` such that `pref[i] > 0`. ### Task Compute the **maximum possible value of** `score(p)` over all permutations `p` of the array. ### Input - Integer array `a` (may contain negative, zero, and positive values). ### Output - An integer: the maximum number of positive prefix sums achievable. ### Constraints - `1 <= n <= 2 * 10^5` - `-10^9 <= a[i] <= 10^9` - Target time complexity: `O(n log n)` (or better). ### Example - Input: `[2, -1, 2, -3]` - One optimal permutation: `[2, 2, -1, -3]` - Prefix sums: `[2, 4, 3, 0]` → positive prefix sums = `3` → Output: `3`