Zoj 1860:dog & Gopher__zoj

Dog & Gopher Time limit:2 Seconds Memory limit:65536 KB A large field has a Dog and a Gopher. The dog wants to eat the gopher while the Gopher wants to run to safety through one of several gopher holes dug in the the SU Rface of the field.

Neither the dog nor the gopher is a math major; However, neither is entirely stupid. The Gopher decides on a particular gopher hole and heads for this hole in a straight line at a fixed speed. The dog, which is very good at Reading body language, anticipates which hole the Gopher has, chosen, and heads at double th E speed of the gopher to the hole, where it intends to gobble up the gopher. If the dog reaches the hole, the gopher gets gobbled; Otherwise, the Gopher escapes.

You are have been retained by the gopher to select a hole through the It can escape, if which a such hole.

Input

The "a" of input contains four floating point numbers:the (x,y) coordinates of the gopher followed by the (X,y) CO Ordinates of the dog. Subsequent lines of input each contain two floating point numbers:the (x,y) coordinates of a gopher hole. All distances are into metres, to the nearest mm.

Input contains multiple test cases. Subsequent test cases are separated with a single blank line.

Output

Your output for each test case should consist's a single line. If The Gopher can escape the line should read, the Gopher can escape through the hole at (x,y). Identifying Te hole to the nearest mm. otherwise the output line should read "The Gopher cannot escape." If the gopher may escape through more than one hole, choose the one. There are not more than 1000 gopher holes and all coordinates are between-10000 and +10000.

Sample Input

1.000 1.000 2.000 2.000
1.500 1.500

2.000 2.000 1.000 1.000
1.500 1.500
2.500 2.500

Sample Output

The gopher cannot escape.
The gopher can escape through the hole at (2.500,2.500).

Source:university of Waterloo Local Contest 1999.09.25

lost in the valley of the birds, flying alone in this huge world, but do not know where to fly to the side ...

#include <iostream> #include <cstdio> #include <sstream> #include <algorithm> #include <cstr  
Ing> #include <cmath> using namespace std;  
    struct point {double x,y;  
int id;  
};  
Point Hole,ans,dog,gopher;  
Const double EPS = 1e-6; void Dist (point hole,double &todog,double &togop) {Todog =sqrt (dog.x-hole.x) * (dog.x-hole.x) + (dog.y-h  
    OLE.Y) * (DOG.Y-HOLE.Y));  
Togop = sqrt (gopher.x-hole.x) * (gopher.x-hole.x) + (GOPHER.Y-HOLE.Y) * (GOPHER.Y-HOLE.Y));  
} Char str[100];  
        int main () {while (~scanf ("%lf%lf%lf%lf\n", &gopher.x,&gopher.y,&dog.x,&dog.y)) {  
        int flag = 1;  
        Double Todog,togop;  
            while (gets (str)) {if (strlen (str) ==0) break;  
            SSCANF (str, "%LF%LF", &hole.x,&hole.y);  
            Dist (HOLE,TODOG,TOGOP); if (flag && Togop < Todog *0.5) {printF ("The Gopher can escape through the hole at (%.3LF,%.3LF). \ n", hole.x,hole.y);  
            Flag = 0;  
    } if (flag) puts ("The Gopher cannot escape.");  
return 0;   }