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| #include <iostream>
#include <cstdio>
using namespace std;
int n;
double eu, s[10005], k[10005], u[10005], ans;
double getV(int x, double lim){
double l=max(u[x],0.0), r=0x3f3f3f3f, mid;
for(int ii=1; ii<=100; ii++){
mid = (l + r) / 2.0;
if(-1/(2*k[x]*mid*mid*(mid-u[x]))<=lim) l = mid;
else r = mid;
}
return (l+r)/2.0;
}
bool chk1(double lim){
double re=0;
for(int i=1; i<=n; i++){
double v=getV(i, lim);
re += k[i] * s[i] * (v - u[i]) * (v - u[i]);
}
return re<=eu;
}
int main(){
cin>>n>>eu;
for(int i=1; i<=n; i++)
scanf("%lf %lf %lf", &s[i], &k[i], &u[i]);
double l=-0x3f3f3f3f, r=0.0, mid, re;
for(int ii=1; ii<=100; ii++){
mid = (l + r) / 2.0;
if(chk1(mid)) l = mid;
else r = mid;
}
re = (l + r) / 2.0;
for(int i=1; i<=n; i++)
ans += s[i] / getV(i, re);
printf("%.12f\n", ans);
return 0;
}
|