What's the time complexity for some python list operations?

Question

I know it is some kind of basic question but I am not good at the fundamental things. I only know that for stack pop() method pops out the last element with O(1) time.

In python, it's allowed to pop any position in a list as well as to insert an element to any position, ie list.pop(index) and list.insert(index, item) . If the length of a list is n , what's the average time complexity of them?

Besides, is there a difference between list.insert(index, item) and list = list[:index] + [item] + list[index:] ?

Thank you very much for the help!

Answer 1

While list.insert(index, item) does practically the same thing as list = list[:index] + [item] + list[index:] , the python built-in function list.insert was made as a faster way to insert an item into a list. list.insert is more advanced and is not equivalent to list = list[:index] + [item] + list[index:] becuase it uses a different algorithim and is much faster.

The time complexity is O(n), which is approximately n/2.