py binary add

#!/usr/bin/env python

a = [0,1,1,0,1]
b = [1,1,1,1,1]
c = [0,0,0,0,0,0]

p = 0
n = len(a)

for i in xrange(n-1,-1,-1):
    s = a[i]+b[i]+p
    if s>1:
        s = s-2
        p = 1
    else:
        p = 0

    c[i+1] = s

c[0] = p

print c