A C++ program to generate a Pascal’s triangle

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<pre>#include<iostream>
using namespace std;
int fact(int);
main()
{
	int rows,i,j,k;
	cout<<"Enter the numbe of rows you want in the triangle:";
	cin>>rows;
	for(i=0;i<rows;i++)
	{
		//Moving each row by rows-i spaces to get a triangular shape
		for(k=0;k<(rows-i);k++)
		cout<<" ";
		//Loop for printing each row
		for(j=0;j<=i;j++)
		cout<<" "<<fact(i)/(fact(j)*fact(i-j)); //nCr=n!/(r!*(n-r)!)
		cout<<endl;
	}
}

int fact(int i)
{
	int value=1;
	while(i!=0)
	{
		value=value*i;
		i--;
	}
	return value;
}</pre>

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Article by Satish Gandham

Authors bio is coming up shortly. Satish Gandham tagged this post with: C++, Pascals triangle Read 10 articles by Satish Gandham

1. HacK_MiNDeD says:

   April 19, 2009 at 9:20 am

   I needed it…!
   Thanks
2. Tom says:

   June 24, 2009 at 3:54 am

   That’s really slow, though (exponential in the number of rows you want to output) since you have to keep computing factorials over and over again.

   It’s *much* faster to use the fact that each element is the sum of the two above it. This means you need to always store the last row you’ve computed, but that’s not a big deal if you are willing to spend O(n) space.
3. Satish Gandham says:

   July 8, 2009 at 5:43 am

   Hello Tom,
   Thanks for ur comment, i will post the optimized code very soon.
4. dayle says:

   October 21, 2009 at 10:33 am

   guys.., how could you display this program like this:

   *
   *
   * *
   * *
   * * *
   * *
   * *
   *
   *

   given any value for the row..,
5. dayle says:

   October 21, 2009 at 10:34 am

   the same consept as above but displayed sideways.., tnx..,
6. sanket says:

   October 31, 2009 at 2:10 pm

   #include
   #include

   void main()
   {
   clrscr();
   int a[10][11];
   int i,j;
   for(i=0;i<=9;i++)
   {
   for(j=0;j<=10;j++)
   a[i][j]=0;
   }
   a[0][1]=1;
   for(i=1;i<=9;i++)
   {
   for(j=1;j<=10;j++)
   {
   a[i][j]=a[i-1][j-1]+a[i-1][j];
   }
   }

   for(i=0;i=i-5;j–)
   cout<<" ";
   for(j=1;j<=10;j++)
   {
   if(a[i][j]!=0)
   cout<<" "<<a[i][j];
   }
   cout<<"\n";
   }
   }
7. raks says:

   December 18, 2009 at 3:42 am

   guys..wat abt dis program..
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