Expert: Joseph Moore - 8/21/2009

Question
sir
please give me a recursive program in c using functions to print pascal's triangle with 0,1

Answer
Here is the code to print the lines of a Pascal's Triangle.  Note that there is no attempt here to shift the lines to make them look more like a standard triangle.  Think of this as Pascal's Right Triangle, perhaps. :)  I'm also not cleaning up dynamic memory in this, nor am I doing any error checking (such as verifying that the _prevRow pointer isn't NULL).  This is purely an algorithm demonstration, not production-quality code.  If you have further questions, feel free to ask.

#include <stdio.h>
#include <malloc.h>

void pascalTri(int* _prevRow, int _prevRowSize, int _rowsToPrint);

int main()
{
   int startRow = 1;
   pascalTri(&startRow, 1, 16);
}

void pascalTri(int* _prevRow, int _prevRowSize, int _rowsToPrint)
{
   int i;
   for (i = 0; i < _prevRowSize; ++i)
   {
       printf("%d ", _prevRow[i]);
   }
   printf("\n");

   if (_rowsToPrint > 1)
   {
       int* newRow = malloc(sizeof(int) * _prevRowSize + 1);
       
       newRow[0] = newRow[_prevRowSize] = 1;
       for (i = 1; i < _prevRowSize; ++i)
       {
           newRow[i] = _prevRow[i - 1] + _prevRow[i];
       }

       pascalTri(newRow, _prevRowSize + 1, _rowsToPrint - 1);
   }
}