UVa 10341 Solve It

本題題目連結
p*e^-x + q*sin(x) + r*cos(x) + s*tan(x) + t*x² + u = 0
0<=p, r<=20 and -20<=q,s,t<=0

想法：
　　因為題目的係數有範圍限制，使得x越大，f(x)的值就越小，為遞減函數，因此可使用二分搜尋逼近答案。

	#include <cstdio>
	#include <cmath>
	using namespace std;
	#define F(x) (p*exp(-x) + q*sin(x) + r*cos(x) + s*tan(x) + t*pow(x,2) + u)
	int main()
	{
	int p, q, r, s, t, u;
	while (scanf("%d %d %d %d %d %d",&p, &q, &r, &s, &t, &u)!=EOF)
	{
	double Min=0.0, Max=1.0, mid;
	for (int i=0; i<100; i++){
	mid = (Min+Max)/2;
	if (F(mid)>0) Min = mid;
	else Max = mid;
	}
	if (fabs(F(mid)-0) > 1e-10) printf ("No solution\n");
	else printf("%.4lf\n",mid);
	}
	return 0;
	}

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