uva-10341-二分法

题意：已知方程的根在0-1范围内，求解方程的根，如果方程不存在根，那就输出 no solution.

直接二分,保留四位小数.

#include "pch.h"
#include <string>
#include<iostream>
#include<map>
#include<memory.h>
#include<vector>
#include<algorithm>
#include<queue>
#include<vector>
#include<stack>
#include<math.h>
#include<iomanip>


namespace cc
{
    using std::cout;
    using std::endl;
    using std::cin;
    using std::map;
    using std::vector;
    using std::string;
    using std::sort;
    using std::priority_queue;
    using std::greater;
    using std::vector;
    using std::swap;
    using std::stack;


    constexpr double MD = 1e-6;

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

    double cal(double x)
    {
        return
            p * exp(-x) + q * sin(x) + r * cos(x) + s * tan(x)
            + t * x*x + u;

    }

    void solve()
    {
        while (cin >> p >> q >> r >> s >> t >> u)
        {
            double l = 0, r = 1;
            if (cal(l)*cal(r) > 0)
            {
                cout << "No solution" << endl;
                continue;
            }
            while (r - l > MD)
            {
                double m = (l + r) / 2;
                if (cal(m)*cal(l) > 0)
                    l = m;
                else
                    r = m;
            }

            cout << std::setiosflags(std::ios::fixed) << std::setprecision(4) << l << endl;;

        }

    }

};


int main()
{

#ifndef ONLINE_JUDGE
    freopen("d://1.text", "r", stdin);
#endif // !ONLINE_JUDGE
    cc::solve();

    return 0;
}