Question

Suppose a linked list of 20 nodes. The middle node has a data –250. Write the pseudocode to replace the middle node of the linked list with a new node and new data. Assume that the list's head pointer is called head_ptr and the data for the new node is called entry

Answer 1

public boolean insertInMiddle(int data){

    boolean isInserted = false;

    Node node = new Node(data);
    Node temp = head;
    index = 10;
    int i=0;
    if(index >= 0 && index <= 20)){
        isInserted = true;
        if(index == 0){
            if(head_ptr !=null){
                node.nextNode = head_ptr;
                head_ptr.prevNode = node;
                head_ptr = node;
            }else{
                head_ptr = node;
                tail=node;
            }
        }else{
            while(i<index){
                temp = temp.nextNode;
                i++;
            }               
            if(temp == null){
                node.nextNode = temp;
                node.prevNode = tail;
                node.prevNode.nextNode = node;
                tail=node;
            }else{
                node.nextNode = temp;
                node.prevNode = temp.prevNode;
                temp.prevNode = node;
                node.prevNode.nextNode = node;
            }
        }
    }   
    
    return isInserted;
}