Topic: Data Structure using C language. Given a linked list A of length N and an integer B$.$ You need to reverse every alternate B node in the linked list A$.$

Input Format:

$456783296$

$3$

Output Format:

$654783692.$Given below is the program snippet.Fill the areas with necessary code. #include

#include

typedef struct ListNode $\{$

int val;

struct ListNode $*$next;

$\}$ ListNode;

$//$ Function to reverse a segment of the list of length B

ListNode$*$ reverseList$($ListNode$*$ head, int B$)\{$

$//$ TODO: Implement the logic to reverse B nodes of the linked list

$\}$

$//$ Function to reverse every alternate B nodes in the linked list

ListNode$*$ reverseAlternateBNodes$($ListNode$*$ A$,$ int B$)\{$

ListNode dummy;

dummy.next $=$ A;

ListNode $*$prev $=$ &dummy, $*$current $=$ A;

int reverse $=1$; $//$ Flag to decide whether to reverse the group or not

$//$ Main loop to process the list

while $($current$)\{$

ListNode $*$tail $=$ current;

$//$ TODO: Move the tail pointer to the end of the current group

$//$ TODO: Implement logic to reverse every alternate group of B nodes

$\}$

return dummy.next;

$\}$

$//$ Function to append a new node at the end of the list

void append$($ListNode$**$ head$\_$ref, int new$\_$data$)\{$

ListNode$*$ new$\_$node $=($ListNode$*)$malloc$($sizeof$($ListNode$))$;

new$\_$node$->$val $=$ new$\_$data;

new$\_$node$->$next $=$ NULL;

if $(*$head$\_$ref $==$ NULL$)\{$

$*$head$\_$ref $=$ new$\_$node;

return;

$\}$

ListNode$*$ last $=*$head$\_$ref;

while $($last$->$next $!=$ NULL$)$ last $=$ last$->$next;

last$->$next $=$ new$\_$node;

$\}$

$//$ Function to print the linked list

void printList$($ListNode$*$ node$)\{$

while $($node $!=$ NULL$)\{$

printf$("\%$d $",$ node$->$val$)$;

node $=$ node$->$next;

$\}$

printf$("$

$")$;

$\}$

$//$ Main function where execution begins

int main$()\{$

ListNode$*$ head $=$ NULL;

int n$,$ value, B;

printf$("$Enter the number of elements in the list: $")$;

scanf$("\%$d$",$ &n$)$;

printf$("$Enter $\%$d elements:

$",$ n$)$;

for $($int i $=0$; i $<$ n; i$++)\{$

scanf$("\%$d$",$ &value$)$;

append$($&head, value$)$;

$\}$

printf$("$Enter the value of B: $")$;

scanf$("\%$d$",$ &B$)$;

head $=$ reverseAlternateBNodes$($head$,$ B$)$;

printf$("$Modified List: $")$;

printList$($head$)$;

return $0$;

$\}$