URAL1348.GoatintheGarden2[求點到線段的距離]

#include 
#include 
#include 
#include 
#include 
using namespace std;

const double eps = 1e-8;
const double pi = acos(-1);
//點
struct POINT
{
 double x, y;
 POINT(){ }
 POINT(double a, double b){
 x = a;
 y = b;
 }
};
//線段
struct Seg
{
 POINT a, b;
 Seg() { }
 Seg(POINT x, POINT y){
 a = x;
 b = y;
 }
};

//直線
struct Line
{
 POINT a, b;
 Line() {}
 Line(POINT x, POINT y){
 a = x;
 b = y;
 }
};

//叉乘
double cross(POINT o, POINT a, POINT b)
{
 return (a.x - o.x) * (b.y - o.y) - (b.x - o.x) * (a.y - o.y);
}

//求兩點間的距離
double dis(POINT a, POINT b)
{
 return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
Seg s;
POINT p;
double L;
//點到直線的距離..
double PointToLine(POINT p, Line l)
{
 return fabs(cross(p, l.a, l.b)) / dis(l.a, l.b);
}
//線段到直線的距離..
double PointToSeg(POINT p, Seg s)
{
 POINT tmp = p;
 tmp.x += s.a.y - s.b.y;
 tmp.y += s.b.x - s.a.x;
 if(cross(s.a, p, tmp) * cross(s.b, p, tmp) >= 0){
 return min(dis(p, s.a), dis(p, s.b));
 }
 return PointToLine(p, Line(s.a, s.b));
}

void solve()
{
 double ans1 = PointToSeg(p, s), ans2 = max(dis(p, s.a), dis(p, s.b));
 printf("%.2lf\n%.2lf\n", ans1 > L ? ans1 - L : 0, ans2 > L ? ans2 - L : 0);
 return ;
}

int main()
{
// freopen("11.txt", "r", stdin);
 while(~scanf("%lf %lf %lf %lf", &s.a.x, &s.a.y, &s.b.x, &s.b.y)){
 scanf("%lf %lf %lf", &p.x, &p.y, &L);
 solve();
 }
 return 0;
}