1.py

def learning_path(first: str, second: str, third: str, fourth: str, target: str) -> str:
    record: Dict[str, List[str]] = {}
    for i in [first, second, third, fourth]:
        rule = i.split(" ")
        if len(rule) == 1:
            record[rule[0]] = []
        else:
            if rule[0] not in record:
                record[rule[0]] = []
            rule[1:].sort()
            record[rule[0]].extend(rule[1:])
            record[rule[0]].append(rule[0])

    result = record[target]
    if len(result) <= 1:
        return result

    del record[target]

    while True:
        breakable = True
        current_len = len(result)
        for index in range(current_len):
            temp = record.get(result[index], None)
            if temp != None:
                breakable = False
                del record[result[index]]

                if len(temp) >= 2:
                    temp.reverse()
                    del result[index]
                    for t in temp:
                        result.insert(0, t)
        if breakable == True:
            break

    return " ".join(result)

result = learning_path(
    "DataScience calculas stats",
    "calculas counting",
    "stats",
    "counting",
    "DataScience"
)
print(result)