新学期第一个算法大作业就好坑爹。。。

要计算三角形外接圆。。。做模板用吧

# include

# include

double X1,Y1,X2,Y2,X3,Y3,x4,y4,length1,length2,length3;

int a;

void myprintf(double x1,double y1,double x2,double y2,double x3,double y3)

{

char ch;

printf("输入第一个点的坐标值，横纵坐标用逗号隔开(如(0,0)):");

while(scanf("(%lf,%lf)",&X1,&Y1)!=2)

{

while((ch=getchar())!='\n')

{

continue;

}

printf("输入有误，请重新输入第一个点的坐标值，横纵坐标用逗号隔开(如(0,0)):");

}

while((ch=getchar())!='\n')

{

continue;

}

printf("输入第二个点的坐标值，横纵坐标用逗号隔开(如(0,0)):");

while(scanf("(%lf,%lf)",&X2,&Y2)!=2)

{

while((ch=getchar())!='\n')

{

continue;

}

printf("输入有误，请重新输入第二个点的坐标值，横纵坐标用逗号隔开(如(0,0)):");

}

while((ch=getchar())!='\n')

{

continue;

}

printf("输入第三个点的坐标值，横纵坐标用逗号隔开(如(0,0)):");

while(scanf("(%lf,%lf)",&X3,&Y3)!=2)

{

while((ch=getchar())!='\n')

{

continue;

}

printf("输入有误，请重新输入第三个点的坐标值，横纵坐标用逗号隔开(如(0,0)):");

}

while((ch=getchar())!='\n')

{

continue;

}

}

void main()

{

myprintf(X1,Y2,X2,Y2,X3,Y3);

length1=sqrt(pow(X1-X2,2)+pow(Y1-Y2,2));

length2=sqrt(pow(X1-X3,2)+pow(Y1-Y3,2));

length3=sqrt(pow(X2-X3,2)+pow(Y2-Y3,2));

while((length1>=length2+length3)||(length2>=length1+length3)||length3>=length1+length2)

{

printf("输入的三个点不能构成三角形，请重新输入\n");

myprintf(X1,Y2,X2,Y2,X3,Y3);

length1=sqrt(pow(X1-X2,2)+pow(Y1-Y2,2));

length2=sqrt(pow(X1-X3,2)+pow(Y1-Y3,2));

length3=sqrt(pow(X2-X3,2)+pow(Y2-Y3,2));

}

x4=(pow(X2,2)*Y1-pow(X3,2)*Y1-pow(X1,2)*Y2+pow(X3,2)*Y2-pow(Y1,2)*Y2+pow(Y2,2)*Y1+pow(X1,2)*Y3-pow(X2,2)*Y3+pow(Y1,2)*Y3-pow(Y2,2)*Y3-pow(Y3,2)*Y1+pow(Y3,2)*Y2)/(2*(X2*Y1-X3*Y1-X1*Y2+X3*Y2+X1*Y3-X2*Y3));

y4=-(-pow(X1,2)*X2+pow(X2,2)*X1+pow(X1,2)*X3-pow(X2,2)*X3-pow(X3,2)*X1+pow(X3,2)*X2-pow(Y1,2)*X2+pow(Y1,2)*X3+pow(Y2,2)*X1-pow(Y2,2)*X3-pow(Y3,2)*X1+pow(X3,2)*X2)/(2*(X2*Y1-X3*Y1-X1*Y2+X3*Y2+X1*Y3-X2*Y3));

printf("此三角形外心坐标为(%lf,%lf)\n",x4,y4);

}