Solution to "All Your Base" Google Codejam contest in Python http://code.google.com/codejam/contest/189252/dashboard#s=p0

all_your_base.py

#!/usr/bin/python

def distinct(j):
    seen = set() 
    for i in j:
        if i not in seen:
            seen.add(i)
    return seen

def next_index(c):
    if c == 0:
        return 1
    if c == 1:
        return 0
    return c

def solve(j):
    alphabet = distinct(j)
    base = max(2, len(alphabet))
    code = {}
    result = 0
    total = len(j)
    for k, i in enumerate(j):
        if i in code:
            new_val = code[i]
        else:
            new_val = next_index
        result += ((base ^ (total - k)) * new_val) 
        code[i]=new_val

if __name__ == "__main__":
  f = open("A-large-practice.in")
  l = f.readlines()[1:]
  f.close()
  o = open("A-large-py.out", "w")
  for i, j in enumerate(l):
      o.write("Case #%d: %d\n"% (i, solve(j)))
  o.close()

at line 6 why would you check if it exists in set? The whole purpose of using set is that you don't check while adding and be sure that it will return unique element.