K append numbers

#1

node* appendK(node *head,int k){
node *oldHead = head;
node *fast = head;
node *slow = head;
for(long i=0;i < k && fast->next!=NULL ;i++){
fast = fast->next;
}
while(fast->next!=NULL && fast!=NULL){
fast = fast->next;
slow = slow->next;
}
node *newHead = slow->next;
slow->next = NULL;
fast->next = oldHead;
return newHead;
}
Can you explain the algo for this code

#2

@dips123deepali_c25f140838182212
so basically lets understand with example let say linked list is 1->2->2->1->8->5->6 and k is 3 so output is 8->5->6->1->2->2->1.

so oldhead pointer is on 1 which is head right now and take 2 pointer fast and slow points to
head intially.

then Traverse linked list until the value of i less than K and next of fast pointer is not null increment fast pointer.
so now fast is at next 1 .
so then traverse slow and fast until fast->next!=NULL and fast!=NULL.
so Now fast is at last node and slow is at 1.
Now take newhead which points to next of slow which is at 1 and next of slow points to null… and then fast which is at 6 points to old head which is !st 1.
so output is 8->5->6->1->2->2->1.

if still not understand then show this

#3

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