big o - Python: List creation by multiplication operator time complexity

Question

Python What's the time complexity of using

a = [1]*n 

vs.

for i in range(n): 
    a.append(1)

Are both O(n) or does the first O(1)?

Answer 1

The former is O(n), due to the use of PyList_New() with a known size. The latter is slightly worse than O(n), due to the need to resize the list after several appends.