elif op2 == 4:
try:
print('有三种路径可供查询：')
print('1.花费最少')
print('2.时间最短')
print('3.换乘最少')
m = int(input('请输入您要查询的路径种类的序号：'))
if m not in {1,2,3}:
print('请输入合法的序号！')
continue
end_pos = str(input('请输入您的目的地：'))
if end_pos not in all.spots:
print('请输入合法的景点名称！')
continue
if m == 1:
all.get_costshortest(start_pos,end_pos)
sit = int(input('结束请输入0，继续请输入任意整数：'))
elif m == 2:
all.get_timeshortest(start_pos, end_pos)
sit = int(input('结束请输入0，继续请输入任意整数：'))
else:
all.get_transhortest(start_pos, end_pos)
sit = int(input('结束请输入0，继续请输入任意整数：'))
except:
print('请输入合法的景点名称！')
sit = int(input('结束请输入0，继续请输入任意整数：'))
else:
try:
print('多目的地旅游线路查询。')
m = '1'
appr = []
