OJ-Problems-Source/HDOJ/5065_autoAC.cpp

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#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;
int A,B,y;
double ans=0;
double inline f(double x)
{
return A*x*x-(B*sin(x)+y);
}
double inline absf(double x)
{
if(f(x)<0)return -f(x);
return f(x);
}
bool findans(double l,double r)
{
if(f(l)*f(r)>0)return 0;
while(r-l>0.00000001)
{
double mid1=l+(r-l)/3,mid2=r-(r-l)/3;
if(absf(mid1)<=absf(mid2))
r=mid2;
else
l=mid1;
}
ans=l;
return 1;
}
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
scanf("%d%d%d",&A,&B,&y);
bool marks=0;ans=0;
for(double x=0;x<50;x=x+0.3)
{
if(findans(x,x+0.3))
{
marks=1;break;
}
}
if(marks)
printf("%.5lf\n",ans);
else
printf("error\n");
}
return 0;
}