double c = 2*3.14159265358979323846*r;

double result = c;

for ( int i = 1; i < n; i++)

result += playfun ( data[i].x , data[i].y , data.x , data.y );

result += playfun ( data[1].x , data[1].y , data[n].x , data[n].y );

double playfun(double a,double b,double x,double y)

{

return sqrt((a-b)*(a-b)+(x-y)*(x-y));

}

为什么33分？这是我的关键代码

data数据在前面就读过了，设置小数位数也在后面