@[Lycan！](/user/210122) 要用$double$
by OItby @ 2020-01-11 19:21:40
这只是错误之一
by OItby @ 2020-01-11 19:23:24
改正的代码
```cpp
#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;
double x[1100];
double y[1100];
struct dao{
double l,r;
}a[2005];
bool cmp(dao a,dao b){
return a.r<b.r;
}
int main(){int n;
double d;
cin >> n >> d;
bool ds=true;
if(n==0&&d==0){
return 0;
}
for(int i=0;i<n;i++){
cin >> x[i]>> y[i];
a[i].l=x[i]-sqrt(d*d-y[i]*y[i]);
a[i].r=x[i]+sqrt(d*d-y[i]*y[i]);
if(y[i]>d){
ds=false;
}
}
if(!ds){
cout <<-1 << endl;
return 0;
}
sort(a,a+n,cmp);
int ans=1;
double note=a[0].r;
for(int i=1;i<n;i++){
if(a[i].l>note){
ans++;
note=a[i].r;
}
}
cout << ans << endl;
ans=0;
return 0;
}
```
by OItby @ 2020-01-11 19:30:06
@[Lycan！](/user/210122) 希望能对你有帮助
by OItby @ 2020-01-11 19:30:31
注意这里
```cpp
bool cmp(dao a,dao b){
return a.r<b.r;
}
```
by OItby @ 2020-01-11 19:31:01
@[Lycan！](/user/210122) 解释可以参考题解第$4$面的第$1$篇题解，即我的……
by OItby @ 2020-01-11 19:33:47
@[AC黑洞](/user/141448) 谢谢你！！！
by coconutt_ @ 2020-01-11 20:38:07