【noiOJ】p6253

 1 #include <iostream>
 2 #include <cstdio>
 3 using namespace std;
 4 double x;
 5 double judge(double xx)
 6 {
 7     return (2*xx*xx*xx-4*xx*xx+3*xx-6);
 8 }
 9 int main()
10 {
11     double left,right,mid,n,sum1,sum2,sum3;
12     scanf("%lf",&x);
13     left=-10; right=10;
14     while (right>left)
15     {
16         mid=(left+right)/2;
17         sum1=judge(left);
18         sum2=judge(right);
19         sum3=judge(mid);
20         if (sum3==0 || right-left<=x)
21         {
22             printf("%.8lf",mid);
23             return 0;
24         }
25         else
26             if (sum1*sum3<0)
27                 right=mid;
28             else
29                 if (sum2*sum3<0)
30                     left=mid;
31     }
32     printf("No Solotion");
33     return 0;
34 }