# How to print pascal’s triangle in C++

In this tutorial, we will learn how to print pascal’s triangle in c++. A Pascal’s triangle is a simply triangular array of binomial coefficients. Each number can be represented as the sum of the two numbers directly above it. For example-

## Print pascal’s triangle in C++

There are various methods to print a pascal’s triangle. Below is an interesting solution.

If we look closely at the Pascal triangle and represent it in a combination of numbers, it will look like this.

Look at the 4th line. It follows a pattern. The numbers range from the combination(4,0)[n=4 and r=0] to combination(4,4). This pattern follows for the whole triangle and we will use this logic in our code.

The Formula for combination is simple(shown in image):

First, we will calculate the numerator separately and then the denominator.

**Note:** The first line always prints 1.(So we print it in the main function only)

### C++ Code

Here, is the final code implementation:

#include<iostream> using namespace std; int res=1; int fact(int n) { if(n==1||n==0) { return 1; } else { res=n*fact(n-1); return res; } } int combination(int n,int r) { //int num=0,den=0; int num=fact(n); int den=fact(n-r)*fact(r); int result=num/den; return result; } void pascal(int curline,int nlines) { if(curline==nlines) return; int k=curline+1; for(int j=1;j<=k;j++) { int dig=combination(curline,j-1); cout<<dig<<'\t'; } cout<<endl; pascal(curline+1,nlines); } int main() { int nlines; cin>>nlines; cout<<"1"<<endl;//The first line always contains 1 pascal(1,nlines); }

Input:

6

Output:

1 1 1 1 2 1 1 3 3 1 1 4 6 4 1 1 5 10 10 5 1

Also, refer to these similar posts:

Count the number of occurrences of an element in a linked list in c++

Create all possible strings from a given set of characters in c++

Thank you! Please comment for suggestions

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