标签：hduj c++
Intersection
Time Limit: 4000/4000 MS (Java/Others) Memory Limit: 512000/512000 K (Java/Others)
Total Submission(s): 146 Accepted Submission(s): 63
Problem Description
Matt is a big fan of logo design. Recently he falls in love with logo made up by rings. The following figures are some famous examples you may know.
A ring is a 2-D figure bounded by two circles sharing the common center. The radius for these circles are denoted by r and R (r < R). For more details, refer to the gray part in the illustration below.
Matt just designed a new logo consisting of two rings with the same size in the 2-D plane. For his interests, Matt would like to know the area of the intersection of these two rings.
Input
The first line contains only one integer T (T ≤ 105), which indicates the number of test cases. For each test case, the first line contains two integers r, R (0 ≤ r < R ≤ 10).
Each of the following two lines contains two integers xi, yi (0 ≤ xi, yi ≤ 20) indicating the coordinates of the center of each ring.
Output
For each test case, output a single line “Case #x: y”, where x is the case number (starting from 1) and y is the area of intersection rounded to 6 decimal places.
Sample Input
2
2 3
0 0
0 0
2 3
0 0
5 0
Sample Output
Case #1: 15.707963
Case #2: 2.250778
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;
const double w=1e-8;
const double IP=acos(-1.0);
struct node{
double x,y;
}p,q;
double f(node a,double r,node b,double R){
double d=sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
if(d>r+R+w) return 0;
if(fabs(r-R)+w>d){
int rr=min(r,R);
return IP*rr*rr;
}
double x=(r*r+d*d-R*R)/(2*d);
double g1=acos(x/r);
double g2=acos((d-x)/R);
return r*r*g1+R*R*g2-d*r*sin(g1);
}
int main(){
int T,k=1;
cin>>T;
while(T--){
double x1,x2,y1,y2,r1,r2;
cin>>r1>>r2>>x1>>y1>>x2>>y2;
q.x=x1,q.y=y1;
p.x=x2,p.y=y2;
double ans=f(q,r2,p,r2)-f(q,r1,p,r2)-f(q,r2,p,r1)+f(q,r1,p,r1);
printf("CASE #%d: %.6lf\n",k++,ans);
}
return 0;
}
hdu 5120 Intersection
标签：hduj c++
原文地址：http://blog.csdn.net/hyccfy/article/details/41622545
