Write a function that returns the length of the shortest contiguous subarray whose sum of all elements strictly exceeds n.
minLength([5, 8, 2, -1, 3, 4], 9) ➞ 2
minLength([3, -1, 4, -2, -7, 2], 4) ➞ 3
// Shortest subarray whose sum exceeds 4 is: [3, -1, 4]
minLength([1, 0, 0, 0, 1], 1) ➞ 5
minLength([0, 1, 1, 0], 2) ➞ -1
-1.