get all possible configurations in n queens problem

n_queens.py

def conflict(conf):
    for i in range(len(conf) - 1):
        if conf[i] == conf[-1]:
            return True
        if len(conf) - i - 1 == conf[-1] - conf[i]:
            return True
        elif len(conf) - i - 1 == conf[i] - conf[-1]:
            return True
    return False

def n_queen(size, solutions, level=0, config=None):
    if level == size: solutions.append(config)
    else:
        if level == 0:
            config = [None]
            for i in range(size):
                config[level] = i
                n_queen(size, solutions, level+1, config.copy())
        else:
            config.append(None)
            for i in range(size - 1):
                next_pos = (config[level - 1] + i + 1) % size
                config[level] = next_pos
                if not conflict(config):
                    n_queen(size, solutions, level+1, config.copy())

if __name__ == "__main__":
    solutions = []
    n_queen(8, solutions)
    print(len(solutions))