```cpp
bool cmp(stu a,stu b){
if(a.y==b.y&&a.m==b.m&&a.d==b.d)return false; 删了
if(a.y!=b.y)return a.y<b.y;
if(a.m!=b.m)return a.m<b.m;
if(a.d!=b.d)return a.d<b.d;
return a.id<b.id; --> 回去看题
}
```
by Ryuuko @ 2017-09-26 13:16:00