Complexity question on Python 3 lists

Wed Feb 15 13:20:21 EST 2012

What is the cost of calling primes(n) below ? I'm mainly interested in
knowing if the call to append is O(1), even amortized.
Do lists in Python 3 behave like ArrayList in Java (if the capacity
is full, then the array grows by more than 1 element) ?
def sdiv(n) : # n >= 2
 """returns the smallest (prime) divisor of n"""
 if n % 2 == 0 : return 2
 for d in range(3,int(sqrt(n))+1,2) :
 if n % d == 0 : return d
 return n
def isPrime(n) :
 """Returns True iff n is prime"""
 return n >= 2 and n == sdiv(n)
def primes(n) : # n >= 2
 """Returns the list of primes in [2,n]"""
 res = []
 for k in range(2,n+1) :
 if isPrime(k) : res.append(k) # cost O(1) ?
 return res
Thanks,
 franck