UVA10341 solve it 二分

题意：求f(x)=p*e^-x+q*sin(x)+r*cos(x)+s*tan(x)+t*x*x+u=0,0<=x<=1

思路二分；

#include<stdio.h>
#include<math.h>
typedef double dd;
int p,q,r,s,t,u;
dd solve(dd x)
{
    return p*exp(-x)+q*sin(x)+r*cos(x)+s*tan(x)+t*x*x+u;
}

int main()
{

    while(scanf("%d%d%d%d%d%d",&p,&q,&r,&s,&t,&u)!=EOF)
    {
        if(solve(0)<0||solve(1)>0)
        {
            printf("No solution\n");
            continue;
        }
        dd mid=0.5,l=0.0,r=1.0;
        while(fabs(solve(mid))>=0.00000001)//这里也可也写作while(r-l>=0.00000001)
        {
            if(solve(mid)>0)
                l=mid;
            else
                r=mid;
            mid=(l+r)/2.0;
        }
        printf("%.4lf\n",mid);
    }
    return 0;
}