// File; pascals.cpp
// Example of bi-directional linked list
// Builds tabel of binomial coefficients
// Written by Dr. Spiegel, May 1996, updated Nov. 2007

#include <stdio.h>


 struct node {
  float coeff;
  struct node *next;
 };
 typedef struct node NodePtr;

 struct rowrec {
  int num;
  struct rowrec *nextrow;
  NodePtr *thisrow;
 };
 typedef struct rowrec RowPtr;

 
 RowPtr *start;
 int    col,n;

float fac(int n)
{
 if (n<=1) return(1.0);
 else return(n*fac(n-1));
}

float C_n_r(int n,int r)
{return(fac(n)/(fac(n-r)*fac(r)));}

void generate_row(NodePtr **first, int rownum)

{int i;
 NodePtr *p,*q;
 for (i=0;i<=rownum;i++) {
  if (*first != NULL) {
   q=new node;
   p->next=q;
   p=q;
  }
  else p=new node;
  if (*first==NULL) *first=p;
  p->coeff=C_n_r(rownum,i);
  p->next=NULL;
 }
}

void make_table(int n,RowPtr **start)
{int i;
 RowPtr *p;
 *start=new rowrec;
 (*start)->num=0;
 p=*start;
 p->thisrow=NULL;
 p->nextrow=NULL;
 generate_row(&(p->thisrow),0);
 for (i=1;i<=n;i++) {
  p->nextrow=new rowrec;
  p->nextrow->num=p->num+1;
  p=p->nextrow;
  p->thisrow=NULL;
  generate_row(&(p->thisrow),i);
  p->nextrow=NULL;
 }
}

  void printrow(NodePtr *p)
  {while (p!=NULL) {
    printf("%7.0f   ",p->coeff);
    p=p->next;
   }
  }

void print(RowPtr *start)
{float x;
 while (start!=NULL) {
  x=((n-(start->num-1))/2*6)-2;
  /*
  if (start->num % 2 == 0)
    gotoxy(x+2*(n-start->num+3),wherey());
  else gotoxy(x+2*(n-start->num+1),wherey());
  */
  printrow(start->thisrow);
  printf("\n");
  start=start->nextrow;
 }
}


main()
{start=new rowrec;
 printf(" How many rows (starting from 0) should be generated?");
 printf(" Enter a Number between 0 and 12. Larger values cause");
 printf(" Unreadable Results                      >");
 scanf("%d",&n);
 printf("Pascal""s triangle for N=%d\n",n);
 make_table(n,&start);
 print(start);
}