StyleInCode

""" day_07_01.py """

# usage: python3 day_07_01.py


def get(filename):
    """ contents of filename """
    with open(filename, 'r', encoding='utf-8') as infile:
        data = infile.read()

    return data


def test(data, given_solution):
    """ testing """
    assert solve(data) == given_solution


def solve(data):
    """ solve the puzzle """
    splitters = {(r, c): False for r, row in enumerate(data.splitlines())
                 for c, col in enumerate(row) if col in ['S', '^']}

    for (r, c), _ in splitters.items():
        if r == 0:
            splitters[(r, c)] = True
            continue

        for y in range(r - 1, -1, -1):
            if (y, c) in splitters:
                if y == 0:
                    splitters[(r, c)] = True
                break
            splitters[(r, c)] = (splitters.get((y, c - 1), False) or
                                 splitters.get((y, c + 1), False))
            if splitters[(r, c)]:
                break

    return list(splitters.values()).count(True) - 1


if __name__ == '__main__':
    test(get('example01'), 21)

    puzzle = get('input')
    solution = solve(puzzle)

    print(solution)