#include <stdio.h>
#include <conio.h>
#include <alloc.h>
#define MAX1 3
#define MAX2 3
#define MAXSIZE 20
#define TRUE 1
#define FALSE 2
struct sparse
{
int *sp ;
int row ;
int *result ;
} ;
void initsparse ( struct sparse * ) ;
void create_array ( struct sparse * ) ;
int count ( struct sparse ) ;
void display ( struct sparse ) ;
void create_tuple ( struct sparse*, struct sparse ) ;
void display_tuple ( struct sparse ) ;
void prodmat ( struct sparse *, struct sparse, struct sparse ) ;
void searchina ( int *sp, int ii, int*p, int*flag ) ;
void searchinb ( int *sp, int jj, int colofa, int*p, int*flag ) ;
void display_result ( struct sparse ) ;
void delsparse ( struct sparse * ) ;
void main( )
{
struct sparse s[5] ;
int i ;
clrscr( ) ;
for ( i = 0 ; i <= 3 ; i++ )
initsparse ( &s[i] ) ;
create_array ( &s[0] ) ;
create_tuple ( &s[1], s[0] ) ;
display_tuple ( s[1] ) ;
create_array ( &s[2] ) ;
create_tuple ( &s[3], s[2] ) ;
display_tuple ( s[3] ) ;
prodmat ( &s[4], s[1], s[3] ) ;
printf ( "\nResult of multiplication of two matrices: " ) ;
display_result ( s[4] ) ;
for ( i = 0 ; i <= 3 ; i++ )
delsparse ( &s[i] ) ;
getch( ) ;
}
/* initialises elements of structure */
void initsparse ( struct sparse *p )
{
p -> sp = NULL ;
p -> result = NULL ;
}
/* dynamically creates the matrix */
void create_array ( struct sparse *p )
{
int n, i ;
/* allocate memory */
p -> sp = ( int * ) malloc ( MAX1 * MAX2 * sizeof ( int ) ) ;
/* add elements to the array */
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
printf ( "Enter element no. %d: ", i ) ;
scanf ( "%d", &n ) ;
* ( p -> sp + i ) = n ;
}
}
/* displays the contents of the matrix */
void display ( struct sparse s )
{
int i ;
/* traverses the entire matrix */
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
/* positions the cursor to the new line for every new row */
if ( i % 3 == 0 )
printf ( "\n" ) ;
printf ( "%d\t", * ( s.sp + i ) ) ;
}
}
/* counts the number of non-zero elements */
int count ( struct sparse s )
{
int cnt = 0, i ;
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
if ( * ( s.sp + i ) != 0 )
cnt++ ;
}
return cnt ;
}
/* creates an array that stores information about non-zero elements */
void create_tuple ( struct sparse *p, struct sparse s )
{
int r = 0 , c = -1, l = -1, i ;
/* get the total number of non-zero elements */
p -> row = count ( s ) + 1 ;
/* allocate memory */
p -> sp = ( int * ) malloc ( p -> row * 3 * sizeof ( int ) ) ;
/* store information about
total no. of rows, cols, and non-zero values */
* ( p -> sp + 0 ) = MAX1 ;
* ( p -> sp + 1 ) = MAX2 ;
* ( p -> sp + 2 ) = p -> row - 1 ;
l = 2 ;
/* scan the array and store info. about non-zero values
in the 3-tuple */
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
c++ ;
/* sets the row and column values */
if ( ( ( i % 3 ) == 0 ) && ( i != 0 ) )
{
r++ ;
c = 0 ;
}
/* checks for non-zero element,
row, column and non-zero value
is assigned to the matrix */
if ( * ( s.sp + i ) != 0 )
{
l++ ;
* ( p -> sp + l ) = r ;
l++ ;
* ( p -> sp + l ) = c ;
l++ ;
* ( p -> sp + l ) = * ( s.sp + i ) ;
}
}
}
/* displays the contents of the matrix */
void display_tuple ( struct sparse s )
{
int i, j ;
/* traverses the entire matrix */
printf ( "\nElements in a 3-tuple: " ) ;
j = ( * ( s.sp + 2 ) * 3 ) + 3 ;
for ( i = 0 ; i < j ; i++ )
{
/* positions the cursor to the new line for every new row */
if ( i % 3 == 0 )
printf ( "\n" ) ;
printf ( "%d\t", * ( s.sp + i ) ) ;
}
printf ( "\n" ) ;
}
/* performs multiplication of sparse matrices */
void prodmat ( struct sparse *p, struct sparse a, struct sparse b )
{
int sum, k, position, posi, flaga, flagb, i , j ;
k = 1 ;
p -> result = ( int * ) malloc ( MAXSIZE * 3 * sizeof ( int ) ) ;
for ( i = 0 ; i < * ( a.sp + 0 * 3 + 0 ) ; i++ )
{
for ( j = 0 ; j < * ( b.sp + 0 * 3 + 1 ) ; j++ )
{
/* search if an element present at ith row */
searchina ( a.sp, i, &position, &flaga ) ;
if ( flaga == TRUE )
{
sum = 0 ;
/* run loop till there are element at ith row
in first 3-tuple */
while ( * ( a.sp + position * 3 + 0 ) == i )
{
/* search if an element present at ith col.
in second 3-tuple */
searchinb ( b.sp, j, * ( a.sp + position * 3 + 1 ),
&posi, &flagb ) ;
/* if found then multiply */
if ( flagb == TRUE )
sum = sum + * ( a.sp + position * 3 + 2 ) *
* ( b.sp + posi * 3 + 2 ) ;
position = position + 1 ;
}
/* add result */
if ( sum != 0 )
{
* ( p -> result + k * 3 + 0 ) = i ;
* ( p -> result + k * 3 + 1 ) = j ;
* ( p -> result + k * 3 + 2 ) = sum ;
k = k + 1 ;
}
}
}
}
/* add total no. of rows, cols and non-zero values */
* ( p -> result + 0 * 3 + 0 ) = * ( a.sp + 0 * 3 + 0 ) ;
* ( p -> result + 0 * 3 + 1 ) = * ( b.sp + 0 * 3 + 1 ) ;
* ( p -> result + 0 * 3 + 2 ) = k - 1 ;
}
/* searches if an element present at iith row */
void searchina ( int *sp, int ii, int *p, int *flag )
{
int j ;
*flag = FALSE ;
for ( j = 1 ; j <= * ( sp + 0 * 3 + 2 ) ; j++ )
{
if ( * ( sp + j * 3 + 0 ) == ii )
{
*p = j ;
*flag = TRUE ;
return ;
}
}
}
/* searches if an element where col. of first 3-tuple
is equal to row of second 3-tuple */
void searchinb ( int *sp, int jj, int colofa, int *p, int *flag )
{
int j ;
*flag = FALSE ;
for ( j = 1 ; j <= * ( sp + 0 * 3 + 2 ) ; j++ )
{
if ( * ( sp + j * 3 + 1 ) == jj && * ( sp + j * 3 + 0 ) == colofa )
{
*p = j ;
*flag = TRUE ;
return ;
}
}
}
/* displays the contents of the matrix */
void display_result ( struct sparse s )
{
int i ;
/* traverses the entire matrix */
for ( i = 0 ; i < ( * ( s.result + 0 + 2 ) + 1 ) * 3 ; i++ )
{
/* positions the cursor to the new line for every new row */
if ( i % 3 == 0 )
printf ( "\n" ) ;
printf ( "%d\t", * ( s.result + i ) ) ;
}
}
/* deallocates memory */
void delsparse ( struct sparse *s )
{
if ( s -> sp != NULL )
free ( s -> sp ) ;
if ( s -> result != NULL )
free ( s -> result ) ;
}
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