#include<graphics.h>
#include<math.h>
#include<stdio.h>
int main()
{
int gdriver=DETECT,gmode,i,j,k,t=-1;
initgraph(&gdriver,&gmode,"C:\\TURBOC2");
cleardevice();
setbkcolor(WHITE);
printf("plz input NO. ");
scanf("%d",&i);
setcolor(RED);
circle(320,240,200);
for(j=1;j<=i;j++) /*n dian hua xian */
{
for(k=1;k<=i-1;t++,k++)
line(
320+200*cos(t*360/i),
240+200*sin(t*360/i),
320+200*cos((t+k)*360/i),
240+200*sin((t+k)*360/i)
);

}
getch();
closegraph();
return 0;
}