不能重载（）吧
by wdy1028 @ 2021-08-30 13:48:20
```cpp
struct cmp {
bool operator ()(const LL &a,const LL &b) { return a<b; }
};
```
by compl @ 2021-10-31 18:12:54
自己定义的排序函数也要这样:
```
const _T &a
```
by compl @ 2021-10-31 18:14:17