水题，卡了下下精度。
1 #include <cstdio> 2 #include <iostream> 3 #include <cmath> 4 using namespace std ; 5 #define PI acos(-1.0) 6 #define eps 1e-8 7 int judge(double x,double y) 8 { 9 double a; 10 a = x-y; 11 if(a < 0) 12 a = -a; 13 if(a < eps) 14 return 1; 15 else 16 return 0; 17 } 18 int main() 19 { 20 double x,y,lx,rx,ly,ry,a; 21 int t; 22 scanf("%d",&t); 23 while(t--) 24 { 25 scanf("%lf%lf",&x,&y); 26 a = PI/180*120; 27 lx=x*cos(a)-y*sin(a); 28 ly=x*sin(a)+y*cos(a); 29 rx=x*cos(a)+y*sin(a); 30 ry=-x*sin(a)+y*cos(a); 31 if(ly - ry > eps) 32 { 33 swap(ly,ry); 34 swap(lx,rx); 35 } 36 else if(judge(ly,ry)) 37 { 38 if(lx - rx > eps) 39 { 40 swap(ly,ry); 41 swap(lx,rx); 42 } 43 } 44 printf("%.3lf %.3lf %.3lf %.3lf ",lx,ly,rx,ry); 45 } 46 return 0; 47 }