1766.cpp

哈尔滨工业大学ACM 竞赛网上在线试题集锦的源代码

/*  This Code is Submitted by wywcgs for Problem 1766 on 2005-10-20 at 16:05:21 */ 
#include <cstdio>
#include <cstring>
#include <cmath>

class Point {
public:
	double x;
	double y;
	double distance(Point *p) {
		return (x-p->x)*(x-p->x) + (y-p->y)*(y-p->y);
	}
};

int main()
{
	Point g, d, h;
	double dg, dd, ehx, ehy;
	bool esc;
	char line[256];
	
	while(scanf("%lf %lf %lf %lf\n", &g.x, &g.y, &d.x, &d.y) == 4) {
		esc = false;
		while(gets(line)) {
			if(strlen(line) == 0) {
				break;
			} else {
				sscanf(line, "%lf %lf", &h.x, &h.y);
				if(!esc) {
					dg = g.distance(&h);
					dd = d.distance(&h);
					if(dg*4 - dd < 1e-6) {
						ehx = h.x;
						ehy = h.y;
						esc = true;
					}
				}
			}
		}
		if(esc) {
			printf("The gopher can escape through the hole at (%.3lf,%.3lf).\n", ehx, ehy);
		} else {
			printf("The gopher cannot escape.\n");
		}
	}
	
	return 0;
}