https://open.kattis.com/problems/doors
判断一下各个顶点到另一条边的距离就行了
注意不要漏了下面那个门的端点到上面那条边的距离
#include<bits/stdc++.h> using namespace std; const double eps=1e-10; const double pi=acos(-1.0); inline int sgn(double x) { if(x>-eps && x<eps) return 0; if(x>0) return 1; else return -1; } inline double mysqrt(double x) { return sqrt(max(0.0,x)); } struct point { double x,y; point(double a=0,double b=0) { x=a;y=b; } point operator - (const point &b)const { return point(x-b.x,y-b.y); } double norm() { return mysqrt(x*x+y*y); } }; inline double det(const point &a,const point &b) { return a.x*b.y-a.y*b.x; } inline double dot(const point &a,const point &b) { return a.x*b.x+a.y*b.y; } inline double dist(const point &a,const point &b) { return (a-b).norm(); } inline double dis_point_seg(const point &p,const point &s,const point &t) { if(sgn(dot(p-s,t-s))<0) return (p-s).norm(); if(sgn(dot(p-t,s-t))<0) return (p-t).norm(); return fabs(det(s-p,t-p)/dist(s,t)); } double R,l,w,ans; double A,B; inline void prework() { scanf("%lf%lf",&A,&B); } inline void mainwork() { ans=min(l,w);ans=min(ans,R*2); point p,s,t; p=point(0,w);s=point(l,w);t=point(l+l*cos(pi-A),w+l*sin(pi-A)); ans=min(dis_point_seg(p,s,t),ans); p=point(l+l*cos(pi-B),0+l*sin(pi-B)); ans=min(dis_point_seg(p,s,t),ans); s=point(l,w);t=point(10000,w); ans=min(dis_point_seg(p,s,t),ans); p=point(l,w);s=point(l,0);t=point(l+l*cos(pi-B),0+l*sin(pi-B)); ans=min(dis_point_seg(p,s,t),ans); } inline void print() { printf("%.9f\n",ans/2); } int main() { scanf("%lf%lf%lf",&R,&l,&w); int t; scanf("%d",&t); for(int i=1;i<=t;i++) { prework(); mainwork(); print(); } return 0; }
