### DataStructure Program to multiply two polynomials

/#include <stdio.h>
#include <conio.h>
#define MAX 10
struct term
{
int coeff ;
int exp ;
} ;
struct poly
{
struct term t [10] ;
int noofterms ;
} ;
void initpoly ( struct poly *) ;
void polyappend ( struct poly *, int, int ) ;
struct poly polyadd ( struct poly, struct poly ) ;
struct poly polymul ( struct poly, struct poly ) ;
void display ( struct poly ) ;
void main( )
{
struct poly p1, p2, p3 ;
clrscr( ) ;
initpoly ( &p1 ) ;
initpoly ( &p2 ) ;
initpoly ( &p3 ) ;
polyappend ( &p1, 1, 4 ) ;
polyappend ( &p1, 2, 3 ) ;
polyappend ( &p1, 2, 2 ) ;
polyappend ( &p1, 2, 1 ) ;
polyappend ( &p2, 2, 3 ) ;
polyappend ( &p2, 3, 2 ) ;
polyappend ( &p2, 4, 1 ) ;
p3 = polymul ( p1, p2 ) ;
printf ( "\nFirst polynomial:\n" ) ;
display ( p1 ) ;
printf ( "\n\nSecond polynomial:\n" ) ;
display ( p2 ) ;
printf ( "\n\nResultant polynomial:\n" ) ;
display ( p3 ) ;
getch( ) ;
}
/* initializes elements of struct poly */
void initpoly ( struct poly *p )
{
int i ;
p -> noofterms = 0 ;
for ( i = 0 ; i < MAX ; i++ )
{
p -> t[i].coeff = 0 ;
p -> t[i].exp = 0 ;
}
}
/* adds the term of polynomial to the array t */
void polyappend ( struct poly *p, int c, int e )
{
p -> t[p -> noofterms].coeff = c ;
p -> t[p -> noofterms].exp = e ;
( p -> noofterms ) ++ ;
}
/* displays the polynomial equation */
void display ( struct poly p )
{
int flag = 0, i ;
for ( i = 0 ; i < p.noofterms ; i++ )
{
if ( p.t[i].exp != 0 )
printf ( "%d x^%d + ", p.t[i].coeff, p.t[i].exp ) ;
else
{
printf ( "%d", p.t[i].coeff ) ;
flag = 1 ;
}
}
if ( !flag )
printf ( "\b\b " ) ;
}
/* adds two polynomials p1 and p2 */
struct poly polyadd ( struct poly p1, struct poly p2 )
{
int i, j, c ;
struct poly p3 ;
initpoly ( &p3 ) ;
if ( p1.noofterms > p2.noofterms )
c = p1.noofterms ;
else
c = p2.noofterms ;
for ( i = 0, j = 0 ; i <= c ; p3.noofterms++ )
{
if ( p1.t[i].coeff == 0 && p2.t[j].coeff == 0 )
break ;
if ( p1.t[i].exp >= p2.t[j].exp )
{
if ( p1.t[i].exp == p2.t[j].exp )
{
p3.t[p3.noofterms].coeff = p1.t[i].coeff + p2.t[j].coeff ;
p3.t[p3.noofterms].exp = p1.t[i].exp ;
i++ ;
j++ ;
}
else
{
p3.t[p3.noofterms].coeff = p1.t[i].coeff ;
p3.t[p3.noofterms].exp = p1.t[i].exp ;
i++ ;
}
}
else
{
p3.t[p3.noofterms].coeff = p2.t[j].coeff ;
p3.t[p3.noofterms].exp = p2.t[j].exp ;
j++ ;
}
}
return p3 ;
}
/* multiplies two polynomials p1 and p2 */
struct poly polymul ( struct poly p1, struct poly p2 )
{
int coeff, exp ;
struct poly temp, p3 ;
initpoly ( &temp ) ;
initpoly ( &p3 ) ;
if ( p1.noofterms != 0 && p2.noofterms != 0 )
{
int i ;
for ( i = 0 ; i < p1.noofterms ; i++ )
{
int j ;
struct poly p ;
initpoly ( &p ) ;
for ( j = 0 ; j < p2.noofterms ; j++ )
{
coeff = p1.t[i].coeff * p2.t[j].coeff ;
exp = p1.t[i].exp + p2.t[j].exp ;
polyappend ( &p, coeff, exp ) ;
}
if ( i != 0 )
{
p3 = polyadd ( temp, p ) ;
temp = p3 ;
}
else
temp = p ;
}
}
return p3 ;
}