BinarySum

BinarySum

# Given two input binary strings, calculate their sum
s1 = '1'
s2 = '1101'
s1l = list(s1)[::-1]
s2l = list(s2)[::-1]

# Padding
if len(s1l) < len(s2l):
    s1l = s1l + ['0'] * (len(s2l) - len(s1l))
elif len(s2l) < len(s1l):
    s2l = s2l + ['0'] * (len(s1l) - len(s2l))

s = []  # for sum bits
c = '0'  # carry bit
print zip(s1l, s2l)

for s1b, s2b in zip(s1l, s2l):
    if (s1b == '1' and s2b == '0') or (s1b == '0' and s2b == '1'):
        if c == '0':
           s.append('1')
        else:
            s.append('0')
    elif s1b == '0' and s2b == '0':
        if c == '0':
           s.append('0')
        else:
            s.append('1')
            c = '0'
    else:  # both incoming bits are 1's
        if c == '0':
           s.append('0')
           c = 1
        else:
           s.append('1')
if c == 1:
    s.append(1)

print 'Binary sum of {0} and {1} is: {2}'.format(s1, s2, ''.join(s[::-1]))