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三分house到shop的距离，二分这条斜边到cinema的距离
#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#include<math.h>
#include<set>
#include<queue>
#include<vector>
#include<map>
using namespace std;
#define ll int
#define N 90
#define Pi 3.1415926535898
#define eps 1e-10
double t1, t2;
struct node{
double x,y;
}c,h,s;
double dist(double x1,double y1,double x2,double y2){
return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
double dist(node a,node b){
return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
double work(double du){
node x = {s.x*(1-du) + h.x*du, s.y*(1-du)+h.y*du};
double ac = dist(x,c), as = dist(x,s), ah = dist(x,h);
if(ac+ah<=t2&&ac+as<=t1)return min(t2-ah,t1-as);
double l = 0, r = 1.0;
for(int i = 1; i <= 300 ; i++){
double mid = (l+r)/2;
node b = {c.x*(1-mid)+x.x*mid,c.y*(1-mid)+x.y*mid};
double bc = dist(b,c), bs = dist(b, s), bh = dist(b, h);
if(bc+bh<=t2 && bc+bs<=t1) l = mid;
else r = mid;
}
node b = {c.x*(1-l)+x.x*l, c.y*(1-l)+x.y*l};
return dist(b,c);
}
int main(){
ll i, j, u, v;
while(cin>>t1>>t2){
cin>>c.x>>c.y;
cin>>h.x>>h.y;
cin>>s.x>>s.y;
double a = dist(c,s), b = dist(c,h), c = dist(h,s);
if(b+t2>=a+c){printf("%.8lf\n",min(a+t1+c,b+t2));continue;}
t1+=a+eps; t2+=b+eps;
double l = 0, r = 1.0, ans = 0;
for(i = 1; i <= 300; i++){
double mid1 = (l+r)/2.0, mid2 = (mid1+r)/2.0;
double ans1 = work(mid1), ans2 = work(mid2);
if(ans1<ans2) l = mid1;
else r = mid2;
ans = max(ans, max(ans1,ans2));
}
printf("%.8lf\n",ans);
}
return 0;
}Codeforces 8D Two Friends 三分+二分+计算几何,布布扣,bubuko.com
Codeforces 8D Two Friends 三分+二分+计算几何
标签：class blog code http tar com
原文地址：http://blog.csdn.net/qq574857122/article/details/34219915
