hdu 2199
1 //二分查找 2 #include<stdio.h> 3 #include<math.h> 4 #define eps 1e-7 5 double fun(double x) 6 { 7 return 8*pow(x,4)+7*pow(x,3)+2*pow(x,2)+3*x+6; 8 } 9 double bin_search(double Y) 10 { 11 double low=0.0,high=100.0,mid; 12 while(high-low>eps) 13 { 14 mid=(low+high)/2.0; 15 if(fun(mid)<Y) 16 low=mid+eps; 17 else 18 high=mid-eps; 19 } 20 return (low+high)/2; 21 } 22 int main() 23 { 24 int t; 25 double Y,ans; 26 scanf("%d",&t); 27 while(t--) 28 { 29 scanf("%lf",&Y); 30 if(fun(0)<=Y&&Y<=fun(100)) 31 { 32 ans=bin_search(Y); 33 printf("%.4lf\n",ans); 34 } 35 else 36 printf("No solution!\n"); 37 } 38 return 0; 39 }