Pascals.cpp File Reference

#include <stdio.h>

Include dependency graph for Pascals.cpp:

Classes
struct	node
struct	rowrec
Typedefs
typedef node	NodePtr
typedef rowrec	RowPtr
Functions
float	fac (int n)
float	C_n_r (int n, int r)
void	generate_row (NodePtr **first, int rownum)
void	make_table (int n, RowPtr **start)
void	printrow (NodePtr *p)
void	print (RowPtr *start)
	main ()
Variables
RowPtr *	start
int	col
int	n

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Typedef Documentation

typedef struct node NodePtr

typedef struct rowrec RowPtr

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Function Documentation

float C_n_r	(	int	n,
		int	r
	)

Compute the binomial coefficient.

Parameters:

	n	n in C(n,r)
	r	r in C(n,r)

Returns:

C(n,r)

{return(fac(n)/(fac(n-r)*fac(r)));}

float fac

(

int

n

)

Compute the factorial of an integer.

Parameters:

n

the value for whose factorial will be computed

Returns:

the factorial of n

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

void generate_row	(	NodePtr **	first,
		int	rownum
	)

Generate a row of Pascal's Triangle.

Parameters:

	first	The data structure holding the triangle
	rownum	Row to generate

{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;
 }
}

main

(

)

Get rows and create triangle

{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);
}

void make_table	(	int	n,
		RowPtr **	start
	)

Create Pascal's triangle

Parameters:

	n	Rows to generate
	start	The data structure holding the triangle

{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 print

(

RowPtr *

start

)

Print the entire Triangle

Parameters:

start

rowptr heading first row

{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;
 }
}

void printrow

(

NodePtr *

p

)

Print a single row of the triangle.

Parameters:

p

Pointer to first element in row

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

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Variable Documentation

int col

int n

RowPtr* start

Global variable is not necessary?

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