Solve It +uva+赤果果的二分

Problem F

Solve It

Input: standard input

Output: standard output

Time Limit: 1 second

Memory Limit: 32 MB

Solve the equation:
        p*e^-x + q*sin(x) + r*cos(x) + s*tan(x) + t*x² + u = 0
        where 0 <= x <= 1.

Input

Input consists of multiple test cases and terminated by an EOF. Each test case consists of 6 integers in a single line: p, q, r, s, t and u (where 0 <= p,r <= 20 and -20 <= q,s,t <= 0). There will be maximum 2100 lines in the input file.

Output

For each set of input, there should be a line containing the value of x, correct upto 4 decimal places, or the string "No solution", whichever is applicable.

Sample Input

0 0 0 0 -2 1

1 0 0 0 -1 2

1 -1 1 -1 -1 1

Sample Output

0.7071

No solution

0.7554

解决方案：二分枚举即可。

代码：
#include<iostream>#include<cstdio>#include<cmath>#include<complex>using namespace std;double p,q,r,s,t,u;double sum(double x){ return ( p*exp(-1.0*x) + q*sin(x) + r*cos(x) + s*tan(x) + t*x*x + u );}int main(){   while(~scanf("%lf%lf%lf%lf%lf%lf",&p,&q,&r,&s,&t,&u)){   double low=0.0;   double m;   double high=1.0;   if(sum(0.0)<0.0||sum(1.0)>0.0)   printf("No solution\n");   else{   while(abs(high-low)>=1e-10){   m=(high+low)/2.0;  if(sum(m)>0) low=m;   else high=m;   }   printf("%.4lf\n",low);   }   }   return 0;}