【python 面試題】如何從一堆車票信息中找到旅程(dict)

# 如何從車票中找到旅程
def print_result(inputs):
    # 用來儲存inputs的鍵與值調換之後的信息
    reverse_input = dict()
    for k,v in inputs.items():
        reverse_input[v] = k
        
    start = None
    # 找到起點
    for k,v in inputs.items():
        if k not in reverse_input:
            start = k
            break
        
    if start == None:
        print('輸入不合理')
        return None
    # 從起點出發按照順序遍歷路徑
    to = inputs[start]
    print(start + '-->' + to, end=' ')
    start = to
    while to != None:
        print(',' + start + "-->" + to, end=' ')
        start = to
        to = inputs.get(to, None)

if __name__=="__main__":
    
    inputs = {
            "西安":"成都",
            "北京":"上海",
            "大連":"西安",
            "上海":"大連"
            }
    
    print_result(inputs=inputs)