Pascal Triangle

Q. Write a C program to generate pascal triangle.

OR

Q. Write a C program to print following number triangle :

				1
			1		1
		1		2		1
	1		3		3		1
1		4		6		4		1

Ans.

How to build Pascal triangle:

To build the pascal triangle, start with "1" at the top, then continue placing numbers below it in a triangular pattern. Each number is build just sum of above two number, (except for the edge, which are all ‘1’ and all numbers outside the Triangle are 0's). so

0 row = 1

1 row = adding the two numbers above them to the left and the right

         = (0+1) , (1+0)

         = 1 , 1

2 row = (0+1) , (1+1) , (1+0) 

          = 1 , 2 , 1

3 row = (0+1), (1+2), (2+1), (1+0)

          = 1 , 3 , 3 , 1

4 row = (0+1), (1+3)  , (3+3), (3+1), (1+0)

          =  1 , 4 , 6 , 4 , 1

/*c program for making pascal triangle*/

#include<stdio.h>

#include<conio.h>

long calc( int );

int main()

{

 int i,j,row,pas;

 printf("Enter no. of rows in pascal triangle : ");

 scanf("%d", &row);

 for(i=0; i<row; i++)

 {

   for(j=0; j<=(row-i-1); j++)

     printf(" ");

   for(j=0; j<=i; j++)

   {

     pas=calc(i)/(calc(j)*calc(i-j));

     printf("%ld ",pas); //take single space

   }

   printf("\n");

 }
 getch();

 return 0;

}

long calc( int num)

{

 int x;

 long res=1;

 for(x=1; x<=num; x++)

   res=res*x;

 return (res);

}

Output:-

Figure: Screen shot for pascal triangle C program