How Efficient Is Python's Max Function

The function max() which returns the maximum element from a list . . . what is its running time (in Python 3) in terms of Big O notation?

Solution 1:

It's O(n), since it must check every element. If you want better performance for max, you can use the heapq module. However, you have to negate each value, since heapq provides a min heap. Inserting an element into a heap is O(log n).

Solution 2:

Of course it is O(n) unless you are using a different datastructure supporting the max of a value collection due to some implementation invariant.

Solution 3:

It depends on how you are using it. If you want to maximize based on a function "someFunc", it'll take O(len(l)*k) where k is the time function "someFunc" takes to run.

maxVal = max(l, key=somefunc)

But yes for normal case it should just iterate over the list and find the max using normal compare function.