G57 自适应辛普森积分【计算几何】

#include<bits/stdc++.h>
using namespace std;
const double eps=1e-10;
double a;
double f(double x)
{
    return pow(x, a/x - x);
}
double simpson(double l, double r)
{
    return (r-l)*( f(l) + f(r) + 4*f( (l+r)/2 ) )/6;
}
double asr(double l, double r, double ans)
{
    double m=(l+r)/2, ls=simpson(l, m), rs=simpson(m, r);
    if( fabs(ls+rs-ans) < eps ) return ans;
    return asr(l, m, ls) + asr(m, r, rs);
}
int main()
{
    freopen("a.in", "r", stdin); freopen("a.out", "w", stdout);
    scanf("%lf", &a);
    if(a < 0) {printf("orz\n"); return 0;}
    printf("%.5lf\n", asr(eps, 20, simpson(eps, 20)) ); 
    return 0;
}

G57 自适应辛普森积分【计算几何】

#include<bits/stdc++.h>
using namespace std;
const double eps=1e-10;
double a;
double f(double x)
{
	return pow(x,a/x-x);
}
double simpson(double l,double r)
{
	return (r-l)*( f(l)+f(r)+4*f( (l+r)/2 )  )/6;
}
double asr(double l,double r,double ans)
{
	double m=(l+r)/2,ls=simpson(l,m),rs=simpson(m,r);
	if( fabs(ls+rs-ans)<eps ) return ans;
	return asr(l,m,ls)+asr(m,r,rs);
}
int main()
{
	freopen("a.in","r",stdin);freopen("a.out","w",stdout);
	scanf("%lf",&a);
	if(a<0) {printf("orz\n");return 0;}
	printf("%.5lf\n",asr(eps,20,simpson(eps,20) )   ); 
	return 0;
}