@[hello098](/user/1051265) 建议用while循环
```c
#include <iostream>
using namespace std;
int main(){
double a,b=0,c=2;
cin>>a;
double sum=1;
a-=c;
while (a>0){
a-=c*0.98;
c*=0.98;
sum++;
}
cout<<sum;
}
```
by penguin_is_cool @ 2023-10-18 21:49:56
@[penguin_is_cool](/user/1065176) 其实用for也不是不行
```c++
#include<iostream>
using namespace std;
double s,t=2,sum;
int main(){
cin>>s;
for(int i=1;;i++){
sum+=t;
t*=0.98;
if(sum>=s){
cout<<i;
break;
}
}
return 0;
}
```
by hjsxzz2022 @ 2023-12-12 09:28:19
@[hjsxzz2022](/user/1232509) 我知道，但while可能更简单
by penguin_is_cool @ 2023-12-12 22:12:44