C++ PROGRAM FOR PASCAL MODEL

program:

#include<iostream.h>

#include<conio.h>

void main()

{

int p,q,l,f,m,s,t,v,n=6;
int a[][]=new int[100][100];
l=(2*n)-1;
f=n-1;
a[0][f]=1;
a[n-1][0]=1;
a[n-1][l-1]=1;
for(p=0;p<n;p++)
        {

            for(q=2;q<l;q++)

              {
                 a[p+1][q-1]=a[p][q]+a[p][q-2];
              }
       }
for(p=0;p<n;p++)
             {

                for(q=0;q<l;q++)
                {
                 if(a[p][q]==0)  {cout<<" "; }

                 else { cout<<a[p][q]; }

                 }

             cout<<"\n";

            }

getch();

}

======================================

step1:
Considering basic pascal model
     1
 1       1

let take it as a 2-D array "a" then we have
a[0][0]=nothing or 0
a[0][1]=1
a[0][2]=nothing or 0
a[1][0]=1
a[1][1]=nothing or 0
a[1][2]=1

so for given number of rows say n(here it is 2) we have
   index of first row 0 and last row n-1(here it is 1)
   index of first column 0 and last column 2n-1(here it is 3)
   let l=2n-1
it is 2*3 matrix now.
now onwards you should concider a matrix of 2*3

step2:
in all pascal models it is necessary to have
   * middle element of first row should be 1
         so we have (2n-1) columns find the middle of it it will be n-1.
         let f=n-1
             a[0][f]=1;
   * first element of last row must be 1
         row index of first element of last row n-1
         column index of first element of last row 0
          so a[n-1][0]=1
   * last element of last row must be 1
         row index of last element of last row n-1
         column index of last element of last row l=2n-1
step3:
now we have matrix like this
                  0 1 0
                  1 0 1
in order to understand the concept i will take higher pascal model mean while
consider 
         row0-->            0 0 0 0 1 0 0 0 0
         row1-->            0 0 0 1 0 1 0 0 0
         row2-->            0 0 1 0 2 0 1 0 0
         row3-->            0 1 0 3 0 3 0 1 0
         row4-->            1 0 4 0 6 0 4 0 1
   in this i will tell you how a row is obtained from it's previous row
      row 3 is obtained from row 2:
             0th element of 3rd row= -1th element of 2nd row+ 1st element of 2nd row
                                   = 0+0
                          = 0
             1st element of 3rd row= 0th element of 2nd row+ 2nd element of 2nd row
                                   = 0+1
                   = 1
             2nd element of 3rd row= 1st element of 2nd row+ 3rd element of 2nd row
                                   = 0+0
                                   = 0
             3rd element of 3rd row= 2nd element of 2nd row+ 4th element of 2nd row
                                   = 1+2
                                   = 3
          and so on..
             lets apply general rule :
            (q-1) th element of (p+1) row= qth element of pth row+ (q-2)th element of pth row

                                                   a[0][1]
                                                   a[p][q]
                                                      ^
                                           0          1         0
                                           1          0         1
                                           ^                    ^
                                       a[p+1][q-1]        a[p+1][q+1]
                                       a[1][0]            a[1][1]

         so a[p+1][q-1]=a[p][q]+a[p][q-2];

Step4:
replace all 0s with spaces and print the matrix....