Hdu--2014北京区域赛I

2014-11-29 16:50:02

思路：比赛时没想到这个小容斥。。。回来做了道圆相交模板题，然后把这题秒了。

　　答案 = 大圆交大圆 - 2 × 大圆交小圆 + 小圆交小圆

 1 /*************************************************************************
 2     > File Name: i.cpp
 3     > Author: Nature
 4     > Mail: 564374850@qq.com
 5     > Created Time: Sat 29 Nov 2014 03:55:06 PM CST
 6 ************************************************************************/
 7 
 8 #include <cstdio>
 9 #include <cstring>
10 #include <cstdlib>
11 #include <cmath>
12 #include <vector>
13 #include <map>
14 #include <set>
15 #include <stack>
16 #include <queue>
17 #include <iostream>
18 #include <algorithm>
19 using namespace std;
20 #define lp (p << 1)
21 #define rp (p << 1|1)
22 #define getmid(l,r) (l + (r - l) / 2)
23 #define MP(a,b) make_pair(a,b)
24 typedef long long ll;
25 const int INF = 1 << 30;
26 const double eps = 1e-8;
27 const double PI = acos(-1.0);
28 
29 int T;
30 double r,R;
31 double x[2],y[2];
32 
33 double Cal(double ax,double ay,double ar,double bx,double by,double br){
34     double d = sqrt((ax - bx) * (ax - bx) + (ay - by) * (ay - by));
35     if(d >= ar + br)
36         return 0.0;
37     double minr = min(ar,br);
38     if(d <= fabs(ar - br))
39         return PI * minr * minr;
40     double a1 = acos((ar * ar + d * d - br * br) / (2.0 * ar * d));
41     double a2 = acos((br * br + d * d - ar * ar) / (2.0 * br * d));
42     double ans = -d * ar * sin(a1);
43     ans += a1 * ar * ar + a2 * br * br;
44     return ans;
45 }
46 
47 int main(){
48     scanf("%d",&T);
49     for(int tt = 1; tt <= T; ++tt){
50         scanf("%lf%lf",&r,&R);
51         scanf("%lf%lf%lf%lf",&x[0],&y[0],&x[1],&y[1]);
52         printf("Case #%d: %.6f\n",tt,Cal(x[0],y[0],R,x[1],y[1],R) -
53             2.0 * Cal(x[0],y[0],r,x[1],y[1],R) + Cal(x[0],y[0],r,x[1],y[1],r));
54     }
55     return 0;
56 }

 

posted @ 2014-11-29 16:51  Naturain  阅读(118)  评论(0)    收藏  举报