Question

1. C# code Arrays and Linked Lists:

1. Write C++/Java/C#/Python code to declare an array of linked lists of any primitive type you want. (Array of size 2020) (This could be based on MSDN libraries or the lab) – you do not need to instantiate any of the linked lists to contain any actual values.
   

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2. Based on your code or the lab from 4 or your doubly linked list from assignment 2, write the following methods:
   1. A method to rotate the list by n (where n can be a positive or negative integer), +ve values rotate to the right, -ve values rotate to the left. If this list contains 1 or 0 elements it should do nothing.
      

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2. A method called “secondSwap” which swaps the second element in the list with the second last. (E.g. {A, B, C, D, E, F} - > {A, E, C, D, B, F}. On a list with less than 3 elements it can do nothing.
   
   

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Answer 1

a.) Struct Node {int value; Node* Next }; Node * arptr[2020];

b.) i)

void rotate_by_n(Node** head, int n)
{

Node* curr = *head;
Node* temp = *head;
int length = 1;//store number of nodes
    while (temp->next != NULL) {
        temp = temp->next;
        length++;
    }
if(curr->next==NULL||curr==NULL) //if 0 or 1 node in list
{
      return;
}

    if (n == 0)
        return;
    if(n<0) //for left rotation
    {
    n=-(n);
    if (n > length)
    {
        n = n % length; //if n>count of nodes then we take modulus
    }

    Node* current1 = *head;

    int count1 = 1;
    while (count1 < n && current1 != NULL) {
        current1 = current1->next; // current1 will point to nth node after this loop
        count1++;
    }

    if (current1 == NULL)
        return;

    Node* nthnode = current1;

    while (current1 ->next != NULL)
        current1 = current1->next;

    current1->next = *head; // change to head

    *head = nthnode->next; //change head to (nth+1) node

    nthnode->next = NULL;

    }

    else if(n>0)
    {

    if (n > length)
        n= n%length;

    n= length-n;

    if (n==0||n==length)
        return;

    Node* current1 = *head;
    int count2= 1;
    while (count2 < n && current1 != NULL) {
        current1 = current1->next;
        count2++;
    }

    if (current1 == NULL)
        return ;

    Node* nthnode = current1;
    temp->next = *head;

    *head = nthnode->next;
    nthnode->next = NULL;

    }
}

b) ii)

void secondSwap(Node * head)
{
    Node * temp1=head,*temp2=head->next,*temp3=head,*curr=head;

    while(curr->next->next!=NULL)
    {
        temp3=curr;
        curr=curr->next;

    }
    if (temp1!= NULL)
    temp1->next = curr;
    else
    {
      head = curr;
    }

if (temp3 != NULL)
    temp3->next = temp2;
else
{
    head = temp2;
}
  

Node *temp = curr->next;
curr->next = temp2->next;
temp2->next = temp;

}

void secondSwap(Node ** head)