1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
#include <bits/stdc++.h>
#define all(x) x.begin(),x.end()
#define CLR(i,a) memset(i,a,sizeof(i))
#define fi first
#define se second
#define pb push_back
#define SZ(a) ((int) a.size())
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define ROF(i, a, b) for (int i = (a); i >= (b); --i)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef __int128 i128;
typedef pair<ll,ll> pll;
typedef array<ll,3> arr;
typedef long double DB;
typedef pair<DB,DB> pdd;
typedef pair<ll,bool> plb;
constexpr ll MAXN=static_cast<ll>(1e6)+10,INF=static_cast<ll>(5e18)+3;
constexpr ll mod=static_cast<ll>(1e9)+7;
constexpr DB eps=1e-8;
ll N,K,T;
DB fac[18];
DB L,R;
inline DB binpow(DB x,ll k){
DB res=1;
while(k){
if(k&1) res*=x;
k>>=1;
x*=x;
}
return res;
}
inline DB F(DB x){
DB res=0;
FOR(i,0,N){
res+=fac[i]*binpow(x,i);
}
return res;
}
inline void solve(){
cin>>N>>L>>R;
ROF(i,N,0){
cin>>fac[i];
}
while(R-L>eps){
DB mid=L+(R-L)/2;
if(F(mid-eps)>F(mid+eps)){
R=mid;
}else{
L=mid;
}
}
cout<<setprecision(15)<<L<<"\n";
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
solve();
return 0;
}
|