uva10341 - Solve It

题意：
求满足方程
p ∗ e−x + q ∗ sin(x) + r ∗ cos(x) + s ∗ tan(x) + t ∗ x*x + u = 0
的解x
思路：
这题用数学中在某区间求根的步骤+二分判断来写，比如区间【0,1】中有根，0与1 带入方程后所得的乘积就会小于0点点点
代码如下：

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
using namespace std;

double p, q, r, s, t, u;

double Judge(double x){
    return p*exp(-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 l = 0, r = 1,mid;
        int ok = 1;
        if (Judge(l)*Judge(r) > 0) {
            ok = 0;
        }
        while (r - l > 10e-8) {
            mid = (l + r) / 2;
            if (Judge(l)*Judge(mid) > 0) 
                l = mid;
            else 
                r = mid;

        }
        if (ok)
            printf("%.4f\n", mid);
        else
            printf("No solution\n");
    }
    return 0;
}