sort应该不稳定，要判断输入顺序，可以在结构体里加个num
by Henry2012 @ 2023-05-21 11:38:15
```
bool xtc(Birthday a, Birthday b) {
if (a.year!=b.year){
return a.year<b.year;
}
else if(a.month!=b.month){
return a.month<b.month;
}
else if(a.day!=b.day){
return a.day<b.day;
}
else return a.num<b.num;
}
```
by Henry2012 @ 2023-05-21 11:39:12
```
for (int i=0;i<n;i++) {
cin>>ins[i].name>>ins[i].year>>ins[i].month>>ins[i].day,ins[i].num=i;
}
```
by Henry2012 @ 2023-05-21 11:39:57
好的，谢谢
by qiujiyuan @ 2023-05-21 14:31:00