三分求条，条闭关

#include <bits/stdc++.h>
using namespace std;
const double eps=1e-7;
int n;
double l,r,a[15];
double f(double x){
	double nowx=1,ans=0;
	for(int i=n;i>=1;i--){
		ans+=a[i]*nowx;
		nowx*=x;
	}
	return ans;
}
int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>n>>l>>r;
	for(int i=1;i<=n;i++) cin>>a[i];
	
	l-=eps,r+=eps;
	while(l+2*eps<r){
		double mid=(l+r)/2;
		double lmid=mid-eps,rmid=mid+eps;
		cout<<lmid<<" "<<rmid<<endl;
		if(f(lmid)<f(rmid)) l=lmid;
		else r=rmid;
	}
	
	cout<<l;
	return 0;
}