hammingcode

def encode(message):
   parity = 1
   while len(message)+parity+1 > 2**parity:
      parity += 1
   for i in range(0,parity):
      message = message[:2**i-1]+"_"+message[2**i-1:]
   check = 0
   while check < parity:
      dist = 2**check
      pos = dist-1
      total = 0
      while pos < len(message):
         for i in range(pos,pos+dist):
            try:
               if message[i] != "_":
                 total += int(message[i])
            except IndexError:
               break
         pos += 2*dist
      if total &1 == 1:
         message = message[:dist-1] +"1" +message[dist:]
      else:
         message = message[:dist-1] +"0" +message[dist:]
      check += 1
   return message

def decode(message):
   parity = 1
   while len(message)+parity+1 > 2**parity:
      parity += 1
   check = 0
   wrong = 0
   while check < parity:
      dist = 2**check
      pos = dist-1
      total = 0
      while pos <= len(message):
         for i in range(pos,pos+dist):
            try:
               if message[i] != "_":
                  total += int(message[i])
            except IndexError:
               break
         pos += 2*dist
      if total &1 != 0:
         wrong += dist
      check += 1
   if wrong != 0:
      if message[wrong-1] == "0":
         message = message[:wrong-1] +"1" +message[wrong:]
      else:
         message = message[:wrong-1] +"0" +message[wrong:]
      print("error found, corrected")
   return message
print(encode("100101"))
print(decode("0111001101"))