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三分house到shop的距离，二分这条斜边到cinema的距离
#include #include #include #include #include #include #include #include #include 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