Solving Logic Problems with Python Decorators – Chelsea Troy

In this article, Chelsea states a logic problem:

“Baker, Cooper, Fletcher, Miller, and Smith live on different floors of an apartment house that contains only five floors. Baker does not live on the top floor. Cooper does not live on the bottom floor. Fletcher does not live on either the top or the bottom floor. Miller lives on a higher floor than does Cooper. Smith does not live on a floor adjacent to Fletcher’s. Fletcher does not live on a floor adjacent to Cooper’s. Where does everyone live?”

Chelsea then proceeds to writing a couple of suboptimal functions that solve this and then converges on a more efficient version of brute forcing. Then, because of the way the code is formulated, Chelsea introduces a decorator that solves logic problems like these. The decorator solve must be used around a function that checks the requirements and produces a function that accepts the possible values for each variable. Something like this:

def all_combinations(**kwargs):
    """Produce all combinations of the variables and their possible values,
    respectively the keys and values of the kwargs dictionary."""
    ...

def solve(reqs_function):
    def solver(**kwargs):
        for comb in all_combinations(**kwargs):
            if reqs_function:
                return comb
        raise RuntimeError("Couldn't solve.")

    return solver

@solve
def reqs_function(**kwargs):
    """Checks the reqs of the problem statement."""
    return kwargs["baker"] != 1 and ...