（HDU）2199 -- Can you solve this equation? （你能解决这个问题吗？）

题目链接：https://bak3.vjudge.net/problem/HDU-2199

最基础的二分搜索

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cmath>
 4 #include <iostream>
 5 #include <algorithm>
 6 #include <string>
 7 #include <cstdlib>
 8 
 9 using namespace std;
10 
11 double f(double x)
12 {
13     double ans;
14     ans=8.0*pow(x,4)+7*pow(x,3)+2*pow(x,2)+3*x+6;
15     return ans;
16 }
17 
18 int main()
19 {
20     int t;
21     double y;
22     scanf("%d",&t);
23     while(t--)
24     {
25         int flag=1;
26         double left=0,mid,right=100;
27         scanf("%lf",&y);
28         while(right-left>1e-6)
29         {
30             if(y<f(left)||y>f(right)) {flag=0;break;}
31             mid=(left+right)/2.0;
32             if(f(mid)>=y) right=mid;
33             else if(f(mid)<y)left=mid;
34         }
35         if (flag) printf("%.4lf\n",mid);
36         else printf("No solution!\n");
37     }
38     return 0;
39 }

 

posted @ 2016-12-06 20:52  ACDoge  阅读(152)  评论(0)  编辑  收藏  举报