Advent of Code Day 2: Basic IntCode Machine

aocday2.py

from typing import List, Callable, NamedTuple, Optional, Tuple


def scan(script: str) -> List[int]:
    """ turn a string input into the ints intcode loves to eat"""
    return list(map(int, script.split(",")))


class Operator(NamedTuple):
    code: int
    arity: int
    behavior: Callable


OPERATORS = {
    99: Operator(99, 0, lambda vm, args: vm.exit()),
    1: Operator(
        1, 3, lambda vm, args: vm.put(args[2], vm.at(args[0]) + vm.at(args[1]))
    ),
    2: Operator(
        2, 3, lambda vm, args: vm.put(args[2], vm.at(args[0]) * vm.at(args[1]))
    ),
}


class VM:
    """ The IntCode VM

    Termination
    >>> VM(scan("99")).interpret()
    [99]

    Addition
    >>> VM(scan("1,0,0,3,99")).interpret()
    [1, 0, 0, 2, 99]

    Multiplication
    >>> VM(scan("1,1,1,4,99,5,6,0,99")).test()
    30

    Errors
    >>> all(VM.go(script) == -1 for script in 
    ...    ["1,0,0,8,99", "3000,1,2,3"])
    True
    """

    run: bool = True
    pc: int = 0
    memory: List[int]

    @staticmethod
    def go(script: str) -> int:
        return VM(scan(script)).test()

    def __init__(self, program: List[int]):
        self.memory = program

    def at(self, a: int) -> int:
        return self.memory[a]

    def put(self, a: int, v: int):
        self.memory[a] = v

    def exit(self):
        self.run = False

    def interpret(self) -> List[int]:
        while self.run:
            op = OPERATORS[self.memory[self.pc]]
            self.pc += 1
            args = self.memory[self.pc : self.pc + op.arity]
            self.pc += op.arity
            op.behavior(self, args)
        return self.memory

    def test(self) -> int:
        try:
            if self.run:
                self.interpret()
            return self.memory[0]
        except (
            KeyError,
            IndexError,
        ):  # KeyError indicates bad operator, IndexError indicates trying to deal with an OOB addr
            return -1


class AoCDay2(NamedTuple):
    """ AoC Day 2 - We have an intcode program, but don't know the last running state needed to get it going again.
    >>> input = scan("1,0,0,3,1,1,2,3,1,3,4,3,1,5,0,3,2,10,1,19,1,5,19,23,1,23,5,27,2,27,10,31,1,5,31,35,2,35,6,39,1,6,39,43,2,13,43,47,2,9,47,51,1,6,51,55,1,55,9,59,2,6,59,63,1,5,63,67,2,67,13,71,1,9,71,75,1,75,9,79,2,79,10,83,1,6,83,87,1,5,87,91,1,6,91,95,1,95,13,99,1,10,99,103,2,6,103,107,1,107,5,111,1,111,13,115,1,115,13,119,1,13,119,123,2,123,13,127,1,127,6,131,1,131,9,135,1,5,135,139,2,139,6,143,2,6,143,147,1,5,147,151,1,151,2,155,1,9,155,0,99,2,14,0,0")
    >>> AoCDay2(input).test(9706670, 12, 2) # Part 1
    True
    >>> AoCDay2(input).test(9706670, 9706670, 2)
    False
    >>> AoCDay2(input).solve(19690720)
    (25, 52)
    """

    program: List[int]

    def test(self, goal: int, noun: int, verb: int) -> bool:
        program = self.program[:]
        program[1], program[2] = noun, verb
        return VM(program).test() == goal

    def solve(self, goal) -> Optional[Tuple[int, int]]:
        for n in range(100):
            for v in range(100):
                if self.test(goal, n, v):
                    return (n, v)
        return None


if __name__ == "__main__":
    import doctest

    doctest.testmod(verbose=True)