输入：num = "1432219", k = 3
1. 找出最大值max和最小值min
，详情可参考heLLoword翻译官方下载
Deborah Alsina, chief executive of Arthritis UK, said: "This is a crushing blow for those individuals who have finally made it to the front of the orthopaedic surgery queue after a long time waiting.
2024年12月24日 星期二 新京报