UVA - 10341 Solve It

题意：

给出的方程式，求出其解；

做法：二分法，本来的区域范围是0-1，一直压缩到esp的区域内；

#include <iostream>#include <cmath>#include <cstdio>#include <cstring>using namespace std;#define esp 1e-9int 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() {double x = 0, y = 1;double m,k;double f1 = cal(x);double f2 = cal(y);if (f1*f2 > 0) printf("No solution\n");else {while (y - x > esp) {m = x + (y - x) / 2;k = cal (m);if (k < 0) y = m;  // 求导之后可以知道他是单调递减的，因此k < 0,要复制给yelse x = m;}printf("%.4lf\n",m);}}int main () {while (scanf("%d %d %d %d %d %d",&p,&q,&r,&s,&t,&u) != EOF) {//printf("%d %d %d %d %d %d\n",p,q,r,s,t,u);solve();}return 0;}