经典题...
不知道怎么证单峰函数
三分第一个传送带的位置里套三分另一个传送带的位置，计算答案
#include<bits/stdc++.h> #define ll long long using namespace std; const int maxn=500010,inf=1e9; const double eps=1e-6; int ax,ay,bx,by,cx,cy,dx,dy,p,q,r; void read(int &k) { int f=1;k=0;char c=getchar(); while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar(); while(c<='9'&&c>='0')k=k*10+c-'0',c=getchar(); k*=f; } double dis(double x1,double y1,double x2,double y2) {return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));} double calc(double x,double y) { double lx=cx,ly=cy,rx=dx,ry=dy; while(fabs(rx-lx)>eps||fabs(ry-ly)>eps) { double midx1=lx+(rx-lx)/3,midy1=ly+(ry-ly)/3; double midx2=lx+((rx-lx)/3*2),midy2=ly+((ry-ly)/3*2); double dis1=dis(ax,ay,x,y)/p+dis(x,y,midx1,midy1)/r+dis(midx1,midy1,dx,dy)/q; double dis2=dis(ax,ay,x,y)/p+dis(x,y,midx2,midy2)/r+dis(midx2,midy2,dx,dy)/q; if(dis1-dis2>eps)lx=midx1,ly=midy1; else rx=midx2,ry=midy2; } return dis(ax,ay,x,y)/p+dis(x,y,lx,ly)/r+dis(lx,ly,dx,dy)/q; } int main() { read(ax);read(ay);read(bx);read(by); read(cx);read(cy);read(dx);read(dy); read(p);read(q);read(r); double lx=ax,ly=ay,rx=bx,ry=by; while(fabs(rx-lx)>eps||fabs(ry-ly)>eps) { double midx1=lx+(rx-lx)/3,midy1=ly+(ry-ly)/3; double midx2=lx+((rx-lx)/3*2),midy2=ly+((ry-ly)/3*2); if(calc(midx1,midy1)-calc(midx2,midy2)>eps)lx=midx1,ly=midy1; else rx=midx2,ry=midy2; } printf("%.2lf",calc(lx,ly)); return 0; }