《ACM国际大学生程序设计竞赛-算法与实现-俞勇-清华大学出版社》.pdf

3.1 3.1.1 1 const double eps = 1e-8; 2 int cmp(double x) { 3 if (fabs(x) eps) return 0; 4 if (x 0) return 1; 5 return -1; 6 } 3 113 3.1.2 1 const double pi = acos(-1.0); 2 inline double sqr(double x) { 3 return x * x; 4 } 5 struct point { 6 double x, y; 7 point() {} 8 point(double a, double b): x(a), y(b) {} 9 void input() { 10 scanf(%lf%lf, x, y); 11 } 12 friend point operator + (const point a, const point b) { 114 ACM 13 return point(a.x + b.x, a.y + b.y); 14 } 15 friend point operator - (const point a, const point b) { 16 return point(a.x - b.x, a.y - b.y); 17 } 18 friend bool operator == (const point a, const point b) { 19 return cmp(a.x - b.x) == 0 cmp(a.y - b.y) == 0; 20 } 21 friend point operator * (const point a, const double b) { 22 return point(a.x * b, a.y * b); 23 }