bzoj 1502 计算几何

来源：互联网发布：步步高v205软件java 编辑：程序博客网时间：2024/05/16 13:38

计算几何就是麻烦，
我只想学学辛普森函数和自适应辛普森算法，
计算几何其他内容。。。就理性放弃吧。。。。。。

S(l,r)=(f(l)+4∗f(mid)+f(r))/6

#include<cstdio>#include<cstdlib>#include<cstring>#include<cmath>#include<iostream>#include<algorithm>#define pow2(x) ((x)*(x))const int MAXN = 600 ,INF = 1<<30;const double  eps = 0.0000001;int n ; double alpha;double r0[MAXN] = {0};double h[MAXN] = {0};struct circle{double x,r;}c[MAXN] = {0};struct line{double x1,x2,y1,y2;}l[MAXN] = {0};int dcmp(const double &x){    if(fabs(x) < eps)return 0;    else if(x > 0)   return 1;    else            return -1;}double f(double x){    double h = 0;    for(int i = 1 ;i <= n ;i++)    {        if(c[i].x - c[i].r <= x && x <= c[i].x + c[i].r)        {            h = std::max(h , sqrt(pow2(c[i].r) - pow2(c[i].x - x)));        }        if(i < n && l[i].x1 <= x && x <= l[i].x2)        {            h = std::max(h , l[i].y1+(x-l[i].x1)*(l[i].y2-l[i].y1)/(l[i].x2-l[i].x1));        }    }    return h;}double simpson(const double &fl,const double &fm,const double &fr,const double &l,const double &r){return (r - l)*(fl + 4*fm + fr)/6;}double fun_simpson(const double fll,const double fm ,const double frr ,const double ll ,const double rr){    double m = (ll + rr)/2 , lm = (ll + m)/2, mr = (m + rr)/2, flm = f(lm),fmr = f(mr);     double s = simpson(fll,fm,frr,ll,rr) ;    double sl = simpson(fll,flm,fm,ll,m) ;     double sr = simpson(fm,fmr,frr,m,rr);    if(dcmp(s - (sl + sr)) != 0)    {        sl = fun_simpson(fll,flm,fm,ll,m);        sr = fun_simpson(fm,fmr,frr,m,rr);        s = sl + sr;    }    return s;}int main(){    double ans = 0, ll = INF, rr = -INF , mid;#ifndef ONLINE_JUDGE        freopen("bzoj1502.in","r",stdin);    freopen("bzoj1502.out","w",stdout);#endif      scanf("%d",&n); n = n + 1;    scanf("%lf",&alpha);    for(int i = 1 ; i <= n ;i++)    {      scanf("%lf", &h[i]);        h[i] += h[i-1];    }    for(int i = 1 ; i < n ;i++)      scanf("%lf", &r0[i]);    for(int i = 1 ; i <= n ;i++)    {        c[i].r = r0[i];        c[i].x = h[i] / tan(alpha);        ll = std::min(ll ,c[i].x - c[i].r);        rr = std::max(rr ,c[i].x + c[i].r);    }    for(int i = 1 ; i < n ;i++)    {        l[i].x1 = c[i].x + c[i].r*(c[i].r-c[i+1].r)/(c[i+1].x-c[i].x);        l[i].y1 = sqrt(pow2(c[i].r) - pow2(l[i].x1-c[i].x));        l[i].x2 = c[i+1].x + c[i+1].r*(c[i].r-c[i+1].r)/(c[i+1].x-c[i].x);        l[i].y2 = sqrt(pow2(c[i+1].r) - pow2(l[i].x2-c[i+1].x));    }    mid = (ll + rr)/2;    ans = fun_simpson(f(ll),f(mid),f(rr),ll,rr)*2;    printf("%.2lf",ans);#ifndef ONLINE_JUDGE        fclose(stdin);    fclose(stdout);#endif      return 0;}

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