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Custom pascal triangle ?

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Custom pascal triangle ?

Jul 11th, 2006

Hello to alll programmers out there.

Here i am trying to design a custom pascal triangle where the user can specify the TOP ELEMENT as well as both the CORNER elements.

The problem i am facing is that the prog works well till the 3rd row but starts giving rubbish values after 3rd. Looks like there is some problem with my logic. I want to do this problem using only one array and not two arrays.

Any suggestions?

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#include "stdafx.h"
#include <stdio.h>
const int leftCorner = 1;
const int rightCorner = 1;
const int topElement = 1;
int *pascalTriangle = 0;
int buildTriangle (int tmpPascalRow)
{
int prev, curr, next;
int tmpRow, elementIndex = 0;
int buffer = 0;
if (tmpPascalRow == 1)
{
pascalTriangle[0] = topElement;
return 1;
}
pascalTriangle[0] = leftCorner;
pascalTriangle[1] = rightCorner;
for (tmpRow = 3; tmpRow <= tmpPascalRow; ++tmpRow)
{
pascalTriangle[0] = leftCorner;
pascalTriangle[tmpRow - 1] = rightCorner;
buffer = leftCorner;
for (elementIndex = 1; elementIndex < tmpRow - 1; ++elementIndex)
{
buffer = pascalTriangle[elementIndex]; 
pascalTriangle[elementIndex] += buffer;
}
}
}
 
int main (void)
{
char inputBuffer[10];
int pascalRow = 0;
int index;
 
fputs ("Enter the number of rows required: ", stdout);
fgets (inputBuffer, sizeof (inputBuffer), stdin);
pascalRow = atoi (inputBuffer);
pascalTriangle = (int*) calloc (pascalRow, sizeof (int));
buildTriangle (pascalRow);
for (index = 0; index < pascalRow; ++index)
printf ("%d\t", pascalTriangle[index]);
getchar();
return 0;
}

Last edited by ~s.o.s~; Jul 11th, 2006 at 4:36 am.

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iamthwee

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Re: Custom pascal triangle ?

Jul 11th, 2006

How about some pseudo code for evaluating the row:

Subroutine

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int compute_pascal(int row, int position)
 
    if(position = 1)
      then
        return 1;
      endif
    else if(position = row)
     then
        return 1;
      end elseif
    else
       return compute_pascal(row-1, position) +     
       compute_pascal(row-1, position-1);
    end else
end subroutine
int compute_pascal(int row, int position)

    if(position = 1)
      then
        return 1;
      endif
    else if(position = row)
     then
        return 1;
      end elseif
    else
       return compute_pascal(row-1, position) +     
       compute_pascal(row-1, position-1);
    end else
end subroutine

Main

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    int row, position
    print message "Please input a row : "
    input:row
 
 
 
        for ( int i = 1; i <= row; i++ )
         then
 
          Print: compute_pascal(row, i);
          Print:"     "
        endfor
 
    end main
    int row, position
    print message "Please input a row : "
    input:row

    
        
        for ( int i = 1; i <= row; i++ )
         then
        
          Print: compute_pascal(row, i);
          Print:"     "
        endfor
    
    end main

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Re: Custom pascal triangle ?

Jul 11th, 2006

Formula for each element:

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   R!
--------
C!(R-C)!

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Re: Custom pascal triangle ?

Jul 11th, 2006

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Originally Posted by server_crash

Formula for each element:
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   R!
--------
C!(R-C)!
R! -------- C!(R-C)!

Err...
Please elaborate if possible.
Thanks.

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Re: Custom pascal triangle ?

Jul 11th, 2006

Pascal's triangle is boring. How about something more fractalish:

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#include <iomanip>
#include <iostream>
 
using namespace std;
 
int main()
{
  int rows = 16;
 
  for ( int i = 0; i < rows; i++ ) {
    cout<< setw ( rows - i - 1 ) <<"";
 
    for ( int j = 0; j <= i; j++ )
      cout<< ( ( ~i & j ) ? ' ' : '*' ) <<' ';
 
    cout<<'\n';
  }
 
  cin.get();
}
#include <iomanip>
#include <iostream>

using namespace std;

int main()
{
  int rows = 16;

  for ( int i = 0; i < rows; i++ ) {
    cout<< setw ( rows - i - 1 ) <<"";

    for ( int j = 0; j <= i; j++ )
      cout<< ( ( ~i & j ) ? ' ' : '*' ) <<' ';

    cout<<'\n';
  }

  cin.get();
}

>Here i am trying to design a custom pascal triangle where the user can
>specify the TOP ELEMENT as well as both the CORNER elements.
That's not very logical. Can you give a few examples?

>Err...
>Please elaborate if possible.
Take note of the ncr function:

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#include <iostream>
 
using namespace std;
 
double factorial ( double n )
{
  return ( n > 1 ) ? n * factorial ( n - 1 ) : 1;
}
 
double ncr ( int n, int r )
{
  return factorial ( n ) / ( factorial ( r ) * factorial ( n - r ) );
}
 
int main()
{
  cout.setf ( ios::fixed, ios::floatfield );
  cout.precision ( 0 );
 
  for ( int i = 0; i < 15; i++ ) {
    for ( int j = 0; j <= i; j++ )
      cout<< right << ncr ( i, j ) <<' ';
 
    cout<<'\n';
  }
 
  cin.get();
}
#include <iostream>

using namespace std;

double factorial ( double n )
{
  return ( n > 1 ) ? n * factorial ( n - 1 ) : 1;
}

double ncr ( int n, int r )
{
  return factorial ( n ) / ( factorial ( r ) * factorial ( n - r ) );
}

int main()
{
  cout.setf ( ios::fixed, ios::floatfield );
  cout.precision ( 0 );

  for ( int i = 0; i < 15; i++ ) {
    for ( int j = 0; j <= i; j++ )
      cout<< right << ncr ( i, j ) <<' ';

    cout<<'\n';
  }

  cin.get();
}

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Re: Custom pascal triangle ?

Jul 11th, 2006

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Originally Posted by Narue

>Here i am trying to design a custom pascal triangle where the user >can specify the TOP ELEMENT as well as both the CORNER >elements.
That's not very logical. Can you give a few examples?

Here is the eg.
3
4 5
4 9 5
4 13 14 5 ...

Though this does not exactly satisfy the rule of pascals triangle it is actually a variation of it which i saw on some web site. It stated the use of Pascal Triangle in composing music tones or something.

•

Originally Posted by Narue

>Err...
>Please elaborate if possible.

Take note of the ncr function:

Dont think this would solve the hybrid pascals problem?

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Originally Posted by Narue

Pascal's triangle is boring. How about something more fractalish:

Whoa this is a beauty ! Miss Narue can you give me other such shapes to derive as execrices and where you got the problem stmt from.

Thanks a lot.

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Re: Custom pascal triangle ?

Jul 12th, 2006

Please can anyone help me on this thing?

Last edited by ~s.o.s~; Jul 12th, 2006 at 2:58 pm.

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Re: Custom pascal triangle ?

Jul 12th, 2006

what thing?

This?

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       3
     4  5
   4  9  5
 4 13  14  5

Where the user gives the three corners, from top to bottom...

Can't you figure that out yourself?

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Re: Custom pascal triangle ?

Jul 13th, 2006

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Originally Posted by iamthwee

what thing?

This?
Help with Code Tags

(Toggle Plain Text)
       
       3
     4  5
   4  9  5
4 13  14  5
3 4 5 4 9 5 4 13 14 5
Where the user gives the three corners, from top to bottom...

Can't you figure that out yourself?

With two arrays yes, but with one array no.
Thats y i wanted the help of you ppl.
I have even posted my effort so far in my first post but i am stuck there so plese help me out.

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Re: Custom pascal triangle ?

#10

Jul 13th, 2006

The first two lines of the triangle must be given. However, after that you can calculate each value on your own as needed. One way is to recognize that if you number the lines of the triangle 1 to x then the maximum number of values per line is also x, that is there are 4 values on the 4th line of the triangle, etc. So you could store the values of the triangle in a two dimensional array of size number of lines by number of lines. Then for each row in the array of index greater than 1:
1) if column index is 0 the value is a given
2) if the column index is the same as the row index then the value is a given
3) otherwise the value of the column at any other given column index less than the row index is the sum of the values at indexes row - 1 and column plus the value at indexes row - 1 and column - 1.

The sample triangle values as indicated in the most recent posts within the 2D array would then look like this:

3
4 5
4 9 5
4 13 14 5

To display the triangle in traditional equilateral triangle display rather than the right triangle display format is a little trickier, but doable, if you must.

Last edited by Lerner; Jul 13th, 2006 at 4:27 pm.