C++ Program to Print Pascal's Triangle

Pascal's Triangle

#include<iostream> 

 using namespace std;

unsigned int factorial(unsigned int const num){

  if( num <=1 )
    return 1;
  else
    return num*factorial(num-1);
}

int main( void ){

  int row = 0;
    
  cout<<"Enter the number of rows: ";
  cin>>row;
  
  //Method 1

  for(unsigned int n=0;n<row;++n){

    //spacing before row depends on how many rows there are
    //row-i = number of space needed before row starts
    
    for(unsigned int j=1;j<(row-n);++j){
      cout<<"  ";
    }

    unsigned int n_factorial = factorial(n);
    //printing the binomial coefficient using combination formula 
    //Number of binomial coefficient on each line
    // is equivalent to the current row number (i.e., the counter i)
    //n choose k or nCk = n!/(k!(n-k)!)
    
    for(unsigned int k=0;k<=n;++k){
      cout<<"   "<<n_factorial/(factorial(n-k)*factorial(k));
    }

    cout<<endl<<endl;
  }
  

  //Method 2 
 
  for(unsigned int n=0;n<row;++n){

    for(unsigned int j=1;j<(row-n);++j){
      cout<<"  ";
    }
    
    unsigned int coeff = 1;
    
    for(unsigned int k=0;k<=n;++k){
      cout<<"   "<<coeff;
      coeff = coeff*(n-k)/(k+1);
    }
  
    cout<<endl<<endl;
  }
 return 0;

}

Output:

Enter number of rows: 5
Method 1:
           1

         1   1

       1   2   1

     1   3   3   1

   1   4   6   4   1

Method 2:
           1

         1   1

       1   2   1

     1   3   3   1

   1   4   6   4   1