题意：
给出一个方程，求解X;
思路：
因为方程是单调递减的，所以二分求解；
代碼:
#include<cstdio> #include<cmath> #include<iostream> #include<algorithm> #include<cstring> #include<string> using namespace std; double p, q, r, s, t, u; double solve(double a) { return p * exp(-a) + q * sin(a) + r * cos(a) + s * tan(a) + t * a * a + u; } int main() { double ll,rr,cur,ans; while(scanf("%lf%lf%lf%lf%lf%lf", &p, &q, &r, &s, &t, &u) != EOF) { ll=0.0, rr=1.0; if(solve(ll)*solve(rr) > 0) { printf("No solution\n"); continue; } while(rr-ll>1e-10) { ans = ll+(rr-ll)/2.0; cur = solve(ans); if(cur>0) { ll=ans; }else rr=ans; } printf("%.4lf\n",ans); } return 0; }