In C++, you need to transpose the linked list, where you move the object in the
ID: 3838295 • Letter: I
Question
In C++, you need to transpose the linked list, where you move the object in the node that is being searched, one node closer to the head. This allows to decrease the cost as the more often the obj is searched the closer it moves to the head of the list. You have a remove function to remove the node from the linked list. You need to create add to the find function where the parameter is the object that is being searched and will be swapped one node closer to the head. Insert your line of code in the find function where the two helper comments are at the end of the find function.
DList<Object>::DList( ) {
header = new DListNode<Object>;
header->next = NULL;
header->prev = NULL;
cost = 0;
}
int TransposeList<Object>::find( const Object &obj ) {
DListNode<Object> *found = DList<Object>::header->next;
int i = 0;
for ( ; found != NULL && found->item != obj; found = found->next, ++i )
++DList<Object>::cost;
if ( found == NULL )
return -1;
if ( found == DList<Object>::header->next )
return 0;
// remove found from the current position
// insert found before previous
}
Explanation / Answer
#include <stdio.h>
#include <conio.h>
#include <malloc.h>
#define MAX1 3
#define MAX2 3
/* structure for col headnode */
struct cheadnode
{
int colno ;
struct node *down ;
struct cheadnode *next ;
} ;
/* structure for row headnode */
struct rheadnode
{
int rowno ;
struct node * right ;
struct rheadnode *next ;
} ;
/* structure for node to store element */
struct node
{
int row ;
int col ;
int val ;
struct node *right ;
struct node *down ;
} ;
/* structure for special headnode */
struct spmat
{
struct rheadnode *firstrow ;
struct cheadnode *firstcol ;
int noofrows ;
int noofcols ;
} ;
struct sparse
{
int *sp ;
int row ;
struct spmat *smat ;
struct cheadnode *chead[MAX2] ;
struct rheadnode *rhead[MAX1] ;
struct node *nd ;
} ;
void initsparse ( struct sparse * ) ;
void create_array ( struct sparse * ) ;
void display ( struct sparse ) ;
int count ( struct sparse ) ;
void create_triplet ( struct sparse *, struct sparse ) ;
void create_llist ( struct sparse * ) ;
void insert ( struct sparse *, struct spmat *, int, int, int ) ;
void show_llist ( struct sparse ) ;
void delsparse ( struct sparse * ) ;
void main( )
{
struct sparse s1, s2 ;
clrscr( ) ;
initsparse ( &s1 ) ;
initsparse ( &s2 ) ;
create_array ( &s1 ) ;
printf ( “ Elements in sparse matrix: ” ) ;
display ( s1 ) ;
create_triplet ( &s2, s1 ) ;
create_llist ( &s2 ) ;
printf ( “ Information stored in linked list : ” ) ;
show_llist ( s2 ) ;
delsparse ( &s1 ) ;
delsparse ( &s2 ) ;
getch( ) ;
}
/* initializes structure elements */
void initsparse ( struct sparse *p )
{
int i ;
/* create row headnodes */
for ( i = 0 ; i < MAX1 ; i++ )
p -> rhead[i] = ( struct rheadnode * ) malloc ( sizeof ( struct rheadnode ) ) ;
/* initialize and link row headnodes together */
for ( i = 0 ; i < MAX1 – 1 ; i++ )
{
p -> rhead[i] -> next = p -> rhead[i + 1] ;
p -> rhead[i] -> right = NULL ;
p -> rhead[i] -> rowno = i ;
}
p -> rhead[i] -> right = NULL ;
p -> rhead[i] -> next = NULL ;
/* create col headnodes */
for ( i = 0 ; i < MAX1 ; i++ )
p -> chead[i] = ( struct cheadnode * ) malloc ( sizeof ( struct cheadnode ) ) ;
/* initialize and link col headnodes together */
for ( i = 0 ; i < MAX2 – 1 ; i++ )
{
p -> chead[i] -> next = p -> chead[i + 1] ;
p -> chead[i] -> down = NULL ;
p -> chead[i] -> colno = i ;
}
p -> chead[i] -> down = NULL ;
p -> chead[i] -> next = NULL ;
/* create and initialize special headnode */
p -> smat = ( struct spmat * ) malloc ( sizeof ( struct spmat ) ) ;
p -> smat -> firstcol = p -> chead[0] ;
p -> smat -> firstrow = p -> rhead[0] ;
p -> smat -> noofcols = MAX2 ;
p -> smat -> noofrows = MAX1 ;
}
/* creates, dynamically the matrix of size MAX1 x MAX2 */
void create_array ( struct sparse *p )
{
int n, i ;
p -> sp = ( int * ) malloc ( MAX1 * MAX2 * sizeof ( int ) ) ;
/* get the element and store it */
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 % MAX2 == 0 )
printf ( “ ” ) ;
printf ( “%d ”, * ( 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 of triplet containing info. about non-zero elements */
void create_triplet ( struct sparse *p, struct sparse s )
{
int r = 0 , c = -1, l = -1, i ;
p -> row = count ( s ) ;
p -> sp = ( int * ) malloc ( p -> row * 3 * sizeof ( int ) ) ;
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
c++ ;
/* sets the row and column values */
if ( ( ( i % MAX2 ) == 0 ) && ( i != 0 ) )
{
r++ ;
c = 0 ;
}
/* checks for non-zero element. Row, column and
non-zero element 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 ) ;
}
}
}
/* stores information of triplet in a linked list form */
void create_llist ( struct sparse *p )
{
int j = 0, i ;
for ( i = 0 ; i < p -> row ; i++, j+= 3 )
insert ( p, p -> smat, * ( p -> sp + j ), * ( p -> sp + j + 1 ),
* ( p -> sp + j + 2) ) ;
}
/* inserts element to the list */
void insert ( struct sparse *p, struct spmat *smat , int r, int c, int v )
{
struct node *temp1, *temp2 ;
struct rheadnode *rh ;
struct cheadnode *ch ;
int i, j ;
/* allocate and initialize memory for the node */
p -> nd = ( struct node * ) malloc ( sizeof ( struct node ) ) ;
p -> nd -> col = c ;
p -> nd -> row = r ;
p -> nd -> val = v ;
/* get the first row headnode */
rh = smat -> firstrow ;
/* get the proper row headnode */
for ( i = 0 ; i < r ; i++ )
rh = rh -> next ;
temp1 = rh -> right ;
/* if no element added in a row */
if ( temp1 == NULL )
{
rh -> right = p -> nd ;
p -> nd -> right = NULL ;
}
else
{
/* add element at proper position */
while ( ( temp1 != NULL ) && ( temp1 -> col < c ) )
{
temp2 = temp1 ;
temp1 = temp1 -> right ;
}
temp2 -> right = p -> nd ;
p -> nd -> right = NULL ;
}
/* link proper col headnode with the node */
ch = p -> smat -> firstcol ;
for ( j = 0 ; j < c ; j++ )
ch = ch -> next ;
temp1 = ch -> down ;
/* if col not pointing to any node */
if ( temp1 == NULL )
{
ch -> down = p -> nd ;
p -> nd -> down = NULL ;
}
else
{
/* link previous node in column with next node in same column */
while ( ( temp1 != NULL ) && ( temp1 -> row < r ) )
{
temp2 = temp1 ;
temp1 = temp1 -> down ;
}
temp2 -> down = p -> nd ;
p -> nd -> down = NULL ;
}
}
void show_llist ( struct sparse s )
{
struct node *temp ;
/* get the first row headnode */
int r = s.smat -> noofrows ;
int i ;
printf ( “ ” ) ;
for ( i = 0 ; i < r ; i++ )
{
temp = s.rhead[i] -> right ;
if ( temp != NULL )
{
while ( temp -> right != NULL )
{
printf ( “Row: %d Col: %d Val: %d ”, temp -> row, temp -> col,
temp -> val ) ;
temp = temp -> right ;
}
if ( temp -> row == i )
printf ( “Row: %d Col: %d Val: %d ”, temp -> row, temp -> col,
temp -> val ) ;
}
}
}
/* deallocates memory */
void delsparse ( struct sparse *p )
{
int r = p -> smat -> noofrows ;
struct rheadnode *rh ;
struct node *temp1, *temp2 ;
int i, c ;
/* deallocate memeory of nodes by traversing rowwise */
for ( i = r – 1 ; i >= 0 ; i– )
{
rh = p -> rhead[i] ;
temp1 = rh -> right ;
while ( temp1 != NULL )
{
temp2 = temp1 -> right ;
free ( temp1 ) ;
temp1 = temp2 ;
}
}
/* deallocate memory of row headnodes */
for ( i = r – 1 ; i >= 0 ; i– )
free ( p -> rhead[i] ) ;
/* deallocate memory of col headnodes */
c = p -> smat -> noofcols ;
for ( i = c – 1 ; i >= 0 ; i– )
free ( p -> chead[i] ) ;
}