# Print Pascal’s triangle of Nth row in C++

In this tutorial, we will learn **how to print Pascal’s triangle in C++** with an algorithm.

Pascal’s triangle is a 2-D array (2-D triangular array) of binomial coefficients. It starts from 1 at the top, then each number placed below in the triangular pattern is the sum of the above two numbers.

## Algorithm: Pascal’s triangle

- declares an initialize a variable ‘n’ for the number of rows.
- start an outer loop for ‘i’ to ‘n’.
- make an inner loop for ‘j’ to “n-1″, print a single space (” “) and close the loop.
- make another inner loop for ‘j’ to ‘i’
- print nCr or C(n, r) for each ‘i’ and ‘j’ and close the loop. (means iCj or C(i, j))
- change the line after each second inner loop (for every ‘i’ after the inner loop)

## C++ program to print Pascal’s triangle

#include<iostream> using namespace std; int factorial(int); int nCr(int, int); int main(){ int n, i, j; cout<<"Enter the number of rows: "; cin>>n; for(int i = 0;i < n; i++){ //first inner loop to print spaces for(j = 0; j <= n-i; j++) cout<<" "; //second inner loop to print combination for each i and j for(j = 0; j <= i; j++) cout<<nCr(i, j)<<" "; cout<<endl; } return 0; } //to find combination or nCr int nCr( int n, int r){ return (factorial(n) / (factorial(n - r) * factorial(r))); } //to find factorial int factorial(int n){ int fact = 1; for(int i = 1; i <= n; i++) fact *= i; return fact; }

**Output: **

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

**Time complexity: **O(n^2)

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