How to print integers in the form of Pascal triangle using C?

Pascal's triangle is the representation of integers in the form of a triangle. One of the famous representations of it is with binomial equations. We can use combinations and factorials to achieve this.

Constructing a Pascal triangle

All values outside the triangle are considered zero (0). The first row is 0 1 0 whereas only 1 acquire a space in Pascal’s triangle, 0s are invisible. The second row is acquired by adding (0+1) and (1+0). The output is sandwiched between two zeroes. The process continues till the required level is achieved.

Programmatically, a Pascal triangle is defined as an array constructed by adding adjacent elements in preceding rows.

Program 1

In this program, we will print integers in the form of Pascal Triangle with Using Array −

 Live Demo

#include <stdio.h>
int fact(int);
int main(){
   int i,rows,j;
   printf("enter no of rows :");
   scanf("%d",&rows);
   for (i = 0; i < rows; i++){
      for (j = 0; j <= (rows- i - 2); j++)
         printf(" ");
      for (j = 0 ; j <= i; j++)
         printf("%d ",fact(i)/(fact(j)*fact(i-j)));
      printf("
");
   }
   return 0;
}
int fact(int n){
   int a;
   int sum = 1;
   for (a = 1; a <= n; a++)
      sum = sum*a;
   return sum;
}

Output

Enter no of rows :5
      1
     1 1
    1 2 1
   1 3 3 1
  1 4 6 4 1

Program 2

Here, we will see printing integers in the form of Pascal Triangle Without Using Array

 Live Demo

#include<stdio.h>
int main(){
   int num,row,i;
   printf("Enter the number of rows: ");
   scanf("%d",&num);
   for(row=1; row<=num; row++){
      int a=1;
      for(i=1; i<=row; i++){
         printf("%d ",a);
         a = a * (row-i)/i;
      }
      printf("
");
   }
   return 0;
}

Output

Enter the number of rows: 6
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1