计算几何 HDOJ 4720 Naive and Silly Muggles

 

题目传送门

/* 题意：给三个点求它们的外接圆，判断一个点是否在园内 计算几何：我用重心当圆心竟然AC了，数据真水:) 正解以后补充，http://www.cnblogs.com/kuangbin/archive/2013/09/11/3315055.html */ #include <cstdio> #include <iostream> #include <algorithm> #include <cstring> #include <string> #include <cmath> using namespace std; int main(void) //HDOJ 4720 Naive and Silly Muggles { //freopen ("E.in", "r", stdin); double x1, y1, x2, y2, x3, y3, xq, yq; double x0, y0; double r; double d; int t, cas = 0; scanf ("%d", &t); while (t--) { scanf ("%lf%lf%lf%lf%lf%lf", &x1, &y1, &x2, &y2, &x3, &y3); scanf ("%lf%lf", &xq, &yq); x0 = (x1 + x2 + x3) / 3.0; y0 = (y1 + y2 + y3) / 3.0; r = (x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0); d = (xq - x0) * (xq - x0) + (yq - y0) * (yq - y0); printf ("Case #%d: ", ++cas); if (d <= r) puts ("Danger"); else puts ("Safe"); } return 0; } /* Case #1: Danger Case #2: Safe Case #3: Safe */