「洛谷P4525」辛普森積分

• 題目鏈接：https://www.luogu.org/problem/P4525

• 題解

  • 辛普森積分模板題 （這是我寫過的最短的題解了

• 代碼

  #include<bits/stdc++.h>
  using namespace std;
  double a,b,c,d,l,r;
  double f(double x) {return (c*x+d)/(a*x+b);}
  double simpson(double l,double r) {return (r-l)*(f(l)+f(r)+4*f((l+r)/2))/6;}
  double area(double l,double r,double eps,double last_area) {
  	double mid=(l+r)/2;
  	double l_area=simpson(l,mid),r_area=simpson(mid,r);
  	if(fabs(last_area-l_area-r_area)<15*eps) return l_area+r_area+(l_area+r_area-last_area)/15;
  	return area(l,mid,eps,l_area)+area(mid,r,eps,r_area);
  }
  int main() {
  	scanf("%lf %lf %lf %lf %lf %lf",&a,&b,&c,&d,&l,&r);
  	printf("%.6lf\n",area(l,r,1e-7,simpson(l,r)));
  }