Big O of min and max in Python

What is the big O of the min and max functions in Python? Are they O(n) or does Python have a better way to find the minimum and maximum of an array? If they are O(n), isn't it better to use a for-loop to find the desired values or do they work the same as a for-loop?

It's O(n). It's a general algorithm, you can't find the max/min in the general case without checking all of them. Python doesn't even have a built-in sorted collection type that would make the check easy to specialize.

A for loop would have the same algorithmic complexity, but would run slower in the typical case, since min/max (on CPython anyway) are running an equivalent loop at the C layer, avoiding bytecode interpreter overhead, which the for loop would incur.

To find the maximum or minimum of a sequence, you must look at each element once, thus you can't get better than O(n).

Of course, Python min and max have O(n) too: docs.

You can write your own min/max function with a for loop and it will have the same complexity, but will be slower because it is not optimized in C.