Meandering Array

An array of integers is defined as being in meandering order when the first two elements are the respective largest and smallest elements in the array and the subsequent elements alternate between its next largest and next smallest elements. In other words, the elements are in order of [first_largest, first_smallest, second_largest, second_smallest,...].

Function
meanderingArray(unsorted: int[]) → int[]
Complete the function meanderingArray in the editor below.
meanderingArray has the following parameters:
int unsorted[n]: the unsorted array
Returns
int[n]: the array sorted in meandering order

Examples
Example 1
unsorted = [-1, 1, 2, 3, -5]
return = [3, -5, 2, -1, 1]
The array [-1, 1, 2, 3, -5] sorted normally is [-5, -1, 1, 2, 3]. Sorted in meandering order, it becomes [3, -5, 2, -1, 1].

Constraints
2≤n≤10^5
-10^6 ≤ unsorted[i] ≤ 10^6
The unsorted array may contain duplicate elements.

The trick is to sort ascending, then place elements with two pointers. Start lo at 0 and hi at n-1. Alternate: take sorted[hi] and decrement, then take sorted[lo] and increment, until the output has n items. That's O(n log n) for the sort and O(n) for the build, which is fine for n up to 10^5. The common pitfalls are odd lengths and duplicates. With odd n, the last element comes from the largest side, and the pointers meet on it, so stop on count, not on pointer crossing. Duplicates need no special handling because you're working off sorted positions. Another mistake is mutating the input when the function should return a new array. If you freeze on the pointer loop during the live OA, StealthCoder can hand you the working version fast.

If this hits your live OA and you blank, StealthCoder solves it in seconds, invisible to the proctor.