# fast_combo_unique.py

# fast_combo_unique.py

from itertools import combinations

def combine(zeros=3, ones=2):
    for indices in combinations(range(zeros+ones), ones):
        item = ['0'] * (zeros+ones)
        for index in indices:
            item[index] = '1'
        yield ''.join(item[::-1])

for z in combine(3, 2):
   print z,

'00011 00101 01001 10001 00110 01010 10010 01100 10100 11000'