http://acm.timus.ru/problem.aspx?space=1&num=1348
1 #include <cstdio> 2 #include <cstring> 3 #include <cmath> 4 #include <algorithm> 5 using namespace std; 6 const double eps=1e-10; 7 8 double dcmp(double x){ 9 if(fabs(x)<eps) return 0; 10 else return x<0?-1:1; 11 } 12 13 double sqr(double x) 14 { 15 return x*x; 16 } 17 struct node 18 { 19 double x,y; 20 }st3,st1,st2; 21 22 double cross(node a,node b) 23 { 24 return (a.x*b.y-a.y*b.x); 25 } 26 double dot(node a,node b) 27 { 28 return (a.x*b.x+a.y*b.y); 29 } 30 double dis(double x1,double y1,double x2,double y2) 31 { 32 return sqrt(sqr(x1-x2)+sqr(y1-y2)); 33 } 34 35 double distance1(node p,node a,node b) 36 { 37 if(a.x==b.x&&a.y==b.y) return dis(p.x,p.y,a.x,a.y); 38 node p1; p1.x=b.x-a.x;p1.y=b.y-a.y; 39 node p2; p2.x=p.x-a.x;p2.y=p.y-a.y; 40 node p3; p3.x=p.x-b.x;p3.y=p.y-b.y; 41 if(dcmp(dot(p1,p2))<0) return dis(p.x,p.y,a.x,a.y); 42 else if(dcmp(dot(p1,p3))>0) return dis(p.x,p.y,b.x,b.y); 43 else return (fabs(cross(p1,p2))/dis(a.x,a.y,b.x,b.y)); 44 } 45 46 int main() 47 { 48 double x1,y1,x2,y2,x3,y3,l; 49 scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2); 50 scanf("%lf%lf%lf",&x3,&y3,&l); 51 st1.x=x1;st1.y=y1; 52 st2.x=x2;st2.y=y2; 53 st3.x=x3;st3.y=y3; 54 double l1=dis(st3.x,st3.y,st1.x,st1.y); 55 double l2=dis(st3.x,st3.y,st2.x,st2.y); 56 double l3=distance1(st3,st1,st2); 57 double min1=min(l1,min(l2,l3)); 58 double max1=max(l1,max(l2,l3)); 59 double ans1=min1-l; 60 double ans2=max1-l; 61 if(ans1<eps) ans1=0; 62 if(ans2<eps) ans2=0; 63 printf("%.2lf ",ans1); 64 printf("%.2lf ",ans2); 65 return 0; 66 }