```cpp
scanf("%lld", &k);
```
读不进ull
by ix35 @ 2019-11-16 22:19:01
解决了qwq
```
k = mid * 2 + 1 - k;
```
mid * 2 爆了ull qwq
by iFroze @ 2019-11-16 22:20:51
n=64时是个bug
by 芷陌陌吖 @ 2019-11-16 22:22:48