int y1 = b[i]; for(int j = i+1; j < k; j++){ int x2 = a[j]; int y2 = b[j]; if(y2==y1 || x1 == x2)continue; double k = 1.0*(y2-y1)/(x2-x1); double b = 1.0*(x2*y1-x1*y2)/(x2-x1); pair<double,double> p = {k,b}; s.insert(p); } } cout...