sol.py

from typing import List

def get_bit(n: int, x: int) -> int:
    bit = n&(1<<x)
    return 0 if bit == 0 else 1

def set_bit(n: int, x: int, b: int) -> int:
    return n&(~(1<<x)) if b == 0 else n|(1<<x)

def encode_chunk(word: str) -> int:
    output = 0
    for i,char in enumerate(map(ord, word)):
        for c,j in enumerate(range(i,32,4)):
            output = set_bit(output, j, get_bit(char, c))
    return output

def encode(text: str) -> List[int]:
    n = 4
    chunks  = [text[i:i+n] for i in range(0, len(text), n)]
    encoded = [encode_chunk(chunk) for chunk in chunks]
    return encoded

def get_last_n_bits(num, n):
    mask = (1 << n) - 1
    return num & mask

def decode_chunk(encoded: int) -> int:
    decoded = 0
    c = 0
    for i in range(8):
        for j in range(i, 32, 8):
            # print(f"setting {j} bit of decoded to ({c}, {get_bit(encoded, c)})")
            decoded = set_bit(decoded, j, get_bit(encoded,c))
            c += 1
    return decoded

def decode(encoded: List[int]) -> List[int]:
    out = ""
    for encoded_chunk in encoded:
        decoded_chunk = decode_chunk(encoded_chunk)
        for i in range(4):
            out += chr(get_last_n_bits(decoded_chunk, 8))
            decoded_chunk = decoded_chunk >> 8
    return out
    


if __name__ == "__main__":
    print(encode("ryan"))
    print(encode("tacocat"))
    print(encode("never odd or even"))
    print(encode("FRED"))
    print(decode(encode("FRED")))
    print(decode(encode("tacocat")))