首页 > 代码库 > POJ 2546 & ZOJ 1597 Circular Area(求两圆相交的面积 模板)
POJ 2546 & ZOJ 1597 Circular Area(求两圆相交的面积 模板)
题目链接:
POJ:http://poj.org/problem?id=2546
ZOJ:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=597
Description
Your task is to write a program, which, given two circles, calculates the area of their intersection with the accuracy of three digits after decimal point.
Input
In the single line of input file there are space-separated real numbers x1 y1 r1 x2 y2 r2. They represent center coordinates and radii of two circles.
Output
The output file must contain single real number - the area.
Sample Input
20.0 30.0 15.0 40.0 30.0 30.0
Sample Output
608.366
Source
Northeastern Europe 2000, Far-Eastern Subregion
题意:
求两圆相交的面积!
直接上模板
代码如下:
#include <cstdio> #include <cstring> #include <cmath> #include <iostream> #include <algorithm> //#include <complex> //#include <iomanip> using namespace std; const double eps = 1e-8; const double PI = acos(-1.0); int sgn(double x) { if(fabs(x) < eps) return 0; if(x < 0) return - 1; else return 1; } struct Point { double x, y; Point(){} Point(double _x, double _y) { x = _x; y = _y; } Point operator -( const Point &b) const { return Point(x - b. x, y - b. y); } //叉积 double operator ^ (const Point &b) const { return x*b. y - y*b. x; } //点积 double operator * (const Point &b) const { return x*b. x + y*b. y; } //绕原点旋转角度B(弧度值),后x,y的变化 void transXY(double B) { double tx = x,ty = y; x = tx* cos(B) - ty*sin(B); y = tx* sin(B) + ty*cos(B); } }; //*两点间距离 double dist( Point a, Point b) { return sqrt((a-b)*(a- b)); } //两个圆的公共部分面积 double Area_of_overlap(Point c1, double r1, Point c2, double r2) { double d = dist(c1,c2); if(r1 + r2 < d + eps) return 0; if(d < fabs(r1 - r2) + eps) { double r = min(r1,r2); return PI*r*r; } double x = (d*d + r1*r1 - r2*r2)/(2*d); double t1 = acos(x / r1); double t2 = acos((d - x)/r2); return r1*r1*t1 + r2*r2*t2 - d*r1*sin(t1); } int main() { double x1, y1, r1, x2, y2, r2; while(~scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&r1,&x2,&y2,&r2)) { Point c1, c2; c1.x = x1; c1.y = y1; c2.x = x2; c2.y = y2; double ans = Area_of_overlap(c1,r1,c2,r2); printf("%.3lf\n",ans); //cout<<setiosflags(ios::fixed)<<setprecision(3)<<ans<<endl; } return 0; }
POJ 2546 & ZOJ 1597 Circular Area(求两圆相交的面积 模板)
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