BM43 包含min函数的栈
https://www.nowcoder.com/practice/4c776177d2c04c2494f2555c9fcc1e49
https://www.nowcoder.com/practice/4c776177d2c04c2494f2555c9fcc1e49
https://www.nowcoder.com/practice/4c776177d2c04c2494f2555c9fcc1e49
https://www.nowcoder.com/practice/d77d11405cc7470d82554cb392585106
https://www.nowcoder.com/practice/a861533d45854474ac791d90e447bafd
https://www.nowcoder.com/practice/54275ddae22f475981afa2244dd448c6
https://www.nowcoder.com/practice/91b69814117f4e8097390d107d2efbe0
https://www.nowcoder.com/practice/a9fec6c46a684ad5a3abd4e365a9d362
https://www.nowcoder.com/practice/37548e94a270412c8b9fb85643c8ccc2