encode

gistfile1.txt

def get_char(c, i):
    return c if i == 1 else '%s%d' % (c, i)

def encode(s):
    if s == '':
        return ''
        
    res = []
    last_char = s[0]
    i = 1
    for c in s[1:]:
        if c != last_char:
            res.append(get_char(last_char, i))
            last_char = c
            i = 1
        else:
            i += 1
            
    res.append(get_char(last_char, i))
    
    return ''.join(res)


def encode2(s):
    if len(s) == 0:
        return s
    last_char = s[0]
    last_pos = 0
    n = 1
    for i, c in enumerate(s[1:]):
        if c != last_char:
            num = bytearray([last_char])
            if n > 1:
                num.extend(str(n).encode())
            s[last_pos:len(num)] = num
            last_pos = last_pos + len(num)
            last_char = c
            n = 1
        else:
            n += 1
            
    num = bytearray([last_char])
    if n > 1:
        num.extend(str(n).encode())
    s[last_pos:len(num)] = num
    last_pos = last_pos + len(num)
    
    return s[:last_pos]