I gave this one a shot, and the code works. Am I on the right track? How can the code be improved? Also, I am unaware of how to determine if this would be linear time or not. Could someone maybe break that determination down for me?

''' Problem statement: Find pairs in an integer array whose sum is equal to n (bonus: do it in linear time)  @author: Anonymous3.1415 '''  def pair_sum_to_n(integer_list, n):     pairs = []     #checks for the occurence of halfs     if not n % 2:         if integer_list.count(n/2) > 1:             pairs.append((n/2, n/2))         integer_set = set(integer_list) - {n/2}     #finds pairs of integers where x + (n - x) = n     for x in integer_set:         if (n - x) in integer_set:             if (n - x, x) not in pairs:                 pairs.append((x, n - x))     return pairs  integer_list = list(map(int, raw_input().strip().split(" "))) pairs = pair_sum_to_n(integer_list, 10) print(pairs)