Intersection of Pair of Lines in the Goven Order of N Lines

#include<stdio.h>
#include<ctype.h>
#include<conio.h>
#include<stdlib.h>
 int i=0; 
	int a1=0 , b1=0 ,c1=0;int K=0;
	int detA =0 , det1 =0 , det2=0 ;int SIZE=0;
	float  *x,*y ; int lines=0;int p=0,q=0,r=0,s=0;
	float x_cor =0 , y_cor =0;
 
	struct COF {
                 int a =0,b=0,c=0,k=0;
                 int count =0;
                 struct COF *next;
	};
 
	struct POINT 
	{
          float x_cord =0 , y_cord=0; int count =0; struct POINT *next;
	};
 
	void CREATE (POINT *A)
       { A=(POINT *) malloc ( sizeof(POINT));return; 
	   }
 
 
	   void  CheckPoint(float cordx , float cordy , POINT *B)
	    { 
	      int TESTX=0 ,TESTY=0; 
	      int FLAGX =0,FLAGY=0 ,STATUS =0;
 
 
 
 
                i=0;
                printf("Entering to CheckPoint PRESS ANY KEY \n");getch();
                do 
                { 
                   printf("i== %d \n",i);
                  if( (B->x_cord <=cordx && B->next->x_cord >= cordx ) || (B->next->x_cord <= cordx && B->x_cord >=cordx ) )  { TESTX=1;}
 
 
 
 
                  if( (B->y_cord <=cordy && B->next->y_cord >= cordy ) || (B->next->y_cord <= cordy && B->y_cord >=cordy ) )  { TESTY=1;}
 
 
 
 
                  B=B->next;
 
                  i++;
 
 
				}
 
				while ( B->next->count!=1  );
 
				printf("EXIT FROM DO WHILE \n");
 
				printf("TESTX= %d  TESTY= %d \n", TESTX ,TESTY);
 
				  if(TESTX==1 && TESTY==1 ) { printf("POINT IS INSIDE \n") ; } 
				  else { printf("POINT IS OUT SIDE \n");  }
 
				  return;
 
		}
 
int main(void)
 
{
 
 
	struct COF *P;
	P=(COF *) malloc(sizeof(COF));
	struct COF *REF;
	REF=(COF *) malloc(sizeof(COF));
	REF=P;
 
		printf("Number of lines N= ");
	    scanf("%d",&lines);
 
	POINT *XY ,*REFPOINT  ;
	 REFPOINT=(POINT *) malloc ( sizeof(POINT));
   for (i=0;i<lines ;i++)
     {   if(i==0) {
	 XY=(POINT *) malloc ( sizeof(POINT));REFPOINT=XY; }
 
 
         else {
 
		        if(i!=lines-1)  
 
		   {
		   XY->next=(POINT *) malloc ( sizeof(POINT));
           XY=XY->next; 
		   }
		        else {XY->next=(POINT *) malloc ( sizeof(POINT));
                       XY->next=REFPOINT; 
          				}
		      }
 
 
		 }	
 
 
 
 
    	x=(float *) malloc(lines*sizeof(float));
	    y=(float *) malloc(lines*sizeof(float));
 
 
	if (x==NULL || y==NULL ) { printf(" X OR Y IS NOT CREATED \n");
	}
 
 
 
    for ( i=0;i<lines ; i++ )
 
	{
	printf("Enter the Coficients of  %d th   line \n", i+1 );
	printf("Enter a[%d] = ", i);
	scanf("%d",&a1);
	printf("Enter b[%d] = ",i);
	scanf("%d",&b1);
	printf("Enter c[%d] = ",i);
	scanf("%d", &c1);
	P->a=a1; P->b=b1;P->c=c1 ;P->k=-1*c1;P->count=i;
	a1=0 ; b1=0 ;c1=0;
	P->next=(COF *) malloc(sizeof(COF));
	if(i==lines-1) { P->next=REF;}
	  else { printf("VALUE OF i is %d : \n",i); P=P->next;}
 
		}	
 
      printf("CIRCULAR LINKED LIST OR COEFICIENT LIST IS CREATED \n ");
 
      i=0;P=REF; 
 
 
      do
 
      {
       	p=0,q=0,r=0,s=0;
 
	printf("CALCULATING DET A DET 1 DET 2  \n ");
	p=P->a; q=P->next->b; r=P->next->a; s=P->b;
 
	detA=p*q - r*s ;
 
	printf("DET A is %d : \n ", detA);
 
	p=0;q=0;r=0;s=0;
 
	p=P->a; q=P->next->k; r=P->next->a; s=P->k;
 
	det1=p*q - r*s ;
	printf("DET 1 IS %d \n",det1);
	p=0;q=0;r=0;s=0;
 
	p=P->next->b; q=P->k; r=P->b; s=P->next->k;
 
	det2=p*q - r*s ;
	printf("DET 2 IS %d \n",det2);
 
	printf("Finding the Intersection : \n ");
 
	*(x+i)=float(det2)/float(detA);
	*(y+i)=float(det1)/float(detA) ;
 
	printf("INTERSECTION is : X=%f  & Y=%f  \n ", *(x+i) , *(y+i)  );
	i++;
	P=P->next;	
		  }
		 while( P->next->count != 1  ) ;
 
	XY=REFPOINT;
 
	for(i=0;i<lines;i++)
	{ XY->x_cord=*(x+i);
	  XY->y_cord=*(y+i);
	  XY->count=i;
	  printf( " X CORD %f Y CORD %f COUNT %d \n ",XY->x_cord,XY->y_cord,XY->count );
 
	  XY=XY->next;
	}
 
 
 
 
	XY=REFPOINT;
 
	 printf("ARE YOU SURE THE LINES IN THE ORDER FORM A REGULAR POLYGON OF %d SIDES : IF SURE ENTER 1 OTHER WISE ENTER 0 :",lines);
                scanf("%d",&K);
	if(K==1)
	{
		printf("ENTER THE CORDINATES OF THE POINTS .\n");
	    printf("ENTER X CORDINATE :");
	    scanf("%f", &x_cor);
	    printf("ENTER Y CORDINATE : ");
	    scanf("%f", &y_cor );
		CheckPoint(x_cor,y_cor,XY);
	}
 
	printf("END \n ");
 
	free(x);free(y);free(XY);free(P);
	getch();
 
	return(0);
 
}