Largest and smallest together

Return the pair (largest, smallest) of a list of at least one number. Finding each one separately takes 2n − 2 comparisons. Do it with at most 3 * n // 2 comparisons, where n is the number of values (3n/2, rounded down).

max_min([3, 7, 1, 9, 4])   # (9, 1), at most 7 comparisons
max_min([5])               # (5, 5), no comparisons needed

The tests pass the values as special number objects that count every comparison made with them (<, <=, >, >=; == is not counted). They behave like normal numbers, and max() and min() count too. Return the values you were given, not copies made with int().

Limits

• Up to 100,000 values, in any order. The limit on comparisons holds for every n, odd or even.