学步园

/*<br /> coder: ACboy<br /> date: 2010-3-21<br /> result: AC<br /> description: UVa 10310 Dog and Gopher<br /> */</p> <p>#include <iostream><br /> #include <cmath><br /> using namespace std;</p> <p>#define EPS 1e-6</p> <p>struct Point {<br /> double x;<br /> double y;<br /> };</p> <p>Point points[1100];<br /> int n;<br /> Point dogPos;<br /> Point gopherPos;</p> <p>double getDis(Point & a, Point & b) {<br /> return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));<br /> }</p> <p>int main()<br /> {<br /> #ifndef ONLINE_JUDGE<br /> freopen("10310.txt", "r", stdin);<br /> #endif<br /> while (cin >> n) {<br /> scanf("%lf%lf%lf%lf", &gopherPos.x, &gopherPos.y, &dogPos.x, &dogPos.y);<br /> int i;<br /> for (i = 0; i < n; i++) {<br /> scanf("%lf%lf", &points[i].x, &points[i].y);<br /> }<br /> int ok = 0;<br /> int pos = -1;<br /> for (i = 0; i < n; i++) {<br /> double dis1 = getDis(gopherPos, points[i]);<br /> double dis2 = getDis(dogPos, points[i]);<br /> if (dis1 * 2 < dis2 || fabs(dis1 * 2 - dis2) < EPS) {<br /> ok = 1;<br /> pos = i;<br /> break;<br /> }<br /> } </p> <p> if (ok){<br /> printf("The gopher can escape through the hole at (%.3lf,%.3lf)./n", points[pos].x, points[pos].y);<br /> } else {<br /> printf("The gopher cannot escape./n");<br /> }<br /> }<br /> return 0;<br /> }<br />