UVa - 10341

Solve the equation:
p ∗ e ^−x + q ∗ sin(x) + r ∗ cos(x) + s ∗ tan(x) + t ∗ x ^2 + u = 0
2 + 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 up to 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

解题思路：

直接二分从0.0000搜到1.0000，搜到就输入没搜到就返回-1;注意这个函数是递减的

二分代码：

double solve()
{
    double low=0,high=1,mid;
    if(fuck(low)*fuck(high)>0)
        return -1;
    while(high-low>1e-8)
    {
        mid = low+(high-low)/2;
        if(fuck(mid)<0)
        high=mid;
        else
        low=mid;
    }
    return low;
}