function minSorted(x) {
    return x[0];
}
The minimum is the lowest number in the array. With a sorted array,
the first element in the array is always the smallest, so this calculation
can be done in one step, or constant time.

@param {Array<number>} x input
@returns {number} minimum value
@example
minSorted([-100, -10, 1, 2, 5]); // => -100