我用的是
```cpp
char getch() {
char ch = getchar();
while (!(ch == 'a' || ch == 's' || ch == 't')) ch = getchar();
return ch;
}
```
这种繁琐又垃圾的写法，求更好的写法/kk
by Micnation_AFO @ 2022-09-29 11:56:06
`'a'<=c&&c<='z'`
by hbhz_zcy @ 2022-09-29 14:40:57