problem_334.py

OPERATORS = {'+', '-', '*', '/'}
TARGET = 24


def possible(arr):
    if len(arr) == 1:
        return arr[0] == TARGET

    new_possibilities = list()
    for si in range(len(arr) - 1):
        for operator in OPERATORS:
            num_1 = arr[si]
            num_2 = arr[si + 1]
            try:
                possibility = \
                    arr[:si] + \
                    [eval("{}{}{}".format(num_1, operator, num_2))] + \
                    arr[si + 2:]
                new_possibilities.append(possibility)
            except Exception:
                pass

    return any([possible(x) for x in new_possibilities])


# Tests
assert possible([5, 2, 7, 8])
assert not possible([10, 10, 10, 10])