day_17.py

from utils import read_multisection_input
from typing import Tuple, List

Registers = dict[str, int]
NewPointer = int | None
Output = int | None
ReturnValue = Tuple[Registers, NewPointer, Output]


def adv(registers: Registers, operand: int) -> ReturnValue:
    numerator = registers["A"]
    value = combos[operand]
    if operand > 3:
        value = registers[value]
    denominator = 2**value
    registers["A"] = numerator // denominator
    return registers, None, None


def bxl(registers: Registers, operand: int) -> ReturnValue:
    registers["B"] = registers["B"] ^ operand
    return registers, None, None


def bst(registers: Registers, operand: int) -> ReturnValue:
    value = combos[operand]
    if operand > 3:
        value = registers[value]
    registers["B"] = value % 8
    return registers, None, None


def jnz(registers: Registers, operand: int) -> ReturnValue:
    jump_to = None
    if registers["A"] != 0:
        jump_to = operand
    return registers, jump_to, None


def bxc(registers: Registers, operand: int) -> ReturnValue:
    registers["B"] = registers["B"] ^ registers["C"]
    return registers, None, None


def out(registers: Registers, operand: int) -> ReturnValue:
    value = combos[operand]
    if operand > 3:
        value = registers[value]
    return registers, None, value % 8


def bdv(registers: Registers, operand: int) -> ReturnValue:
    numerator = registers["A"]
    value = combos[operand]
    if operand > 3:
        value = registers[value]
    denominator = 2**value

    registers["B"] = numerator // denominator
    return registers, None, None


def cdv(registers: Registers, operand: int) -> ReturnValue:
    numerator = registers["A"]
    value = combos[operand]
    if operand > 3:
        value = registers[value]
    denominator = 2**value
    registers["C"] = numerator // denominator

    return registers, None, None


opcodes = {0: adv, 1: bxl, 2: bst, 3: jnz, 4: bxc, 5: out, 6: bdv, 7: cdv}

combos = {0: 0, 1: 1, 2: 2, 3: 3, 4: "A", 5: "B", 6: "C"}


def process(program, registers):
    pointer = 0
    prints = []
    while pointer < len(program):
        opcode = program[pointer]
        operand = program[pointer + 1]

        func = opcodes[opcode]
        registers, pointer_movement, output = func(registers, operand)
        if output is not None:
            prints.append(output)
        if pointer_movement is not None:
            pointer = pointer_movement
        else:
            pointer = pointer + 2

    return prints


def process_simplified(A):
    output = []
    while A != 0:
        a = (A % 8) ^ 1
        b = a ^ 5
        c = A // (2**a)
        res = (b ^ c) % 8
        output.append(res)
        A = A // 8
    return output


def map_registers(section):
    lines = section.split("\n")
    a = int(lines[0].split(": ")[1])
    b = int(lines[1].split(": ")[1])
    c = int(lines[2].split(": ")[1])

    return {"A": a, "B": b, "C": c}


def map_program(section) -> List[int]:
    codes = section.split(": ")[1]
    return [int(code) for code in codes.split(",")]


def part_1():
    registers, program = read_multisection_input(17, [map_registers, map_program])
    output = process(program, registers)
    output = ",".join([str(number) for number in output])

    print(f"Part 1: {output}")
    assert output == "5,0,3,5,7,6,1,5,4"


def part_2():
    _, program = read_multisection_input(17, [map_registers, map_program])

    A = 1
    for i in range(1, len(program) + 1):
        for a in range(A, A + (8**i)):
            output = process_simplified(a)
            if output == program[(-1 * i) :]:
                A = a
                break

        A = A * 8

    result = A // 8
    print(f"Part 2: {result}")
    assert result == 164516454365621


part_1()
part_2()