CODEWITHSUNDEEP
c++list
Podo
Podo

Reputation: 709

LinkedList Node Insertion

I know this is seriously basic stuff, but I for the life of me can't seem to understand how I would go about doing this:

Q: Given the following struct definition for a Node:

struct Node
{
     int value;
     Node* next;
};

And given the declaration:

Node* head;

The following Linked List of Nodes has been constructed, with the head pointer assigned to the Node object 3:

head ----> 3 ----> 9 ----> 34 ----> -5 ----> NULL

Write a single C++ statement that will store the value 34 in the 3rd Node in the variable result:

int result =

Where would be a good place to start? Is this asking me to add an element to the list, or is it adding an entirely new node to the list? So confused!!

Upvotes: 1

Views: 85

Answers (3)

David Vaughan
David Vaughan

Reputation: 121

Linked lists employ a chain concept, where each chain-link along the entire length of the chain is connected at the front of each link.
People represent this in various ways. One example is:

struct Node {
    int value;
    Node* front;
};

Or: 

struct Node {
    int value;
    Node* next;
};

When you establish the head of a linked list, you are creating the first node in the chain:

Node* head;
head = NULL; // this is an empty linked list

Whenever you want to add a node (or "link") to the chain, you pass along the new node to "Head", which keeps track of the chain:

void newNode(int value, Node* head)
{
    Node *node;
    node = new Node*; // or (Node*)malloc(sizeof(Node));
    node->value = value;
    node->next = head;
    head = node;
}

Using this concept, you can add any number of links to your chain. Thomas and warun have good examples of this. Hope this helps.

Upvotes: 2

warun26
warun26

Reputation: 453

head->next->next will point to the third node in the linked list. So,

int result = head->next->next->data;

will store the value in the third node in the list.

The question is asking you to read the third node and store it's value in result.

Upvotes: 2

Thomas
Thomas

Reputation: 2279

example for a loop.

Node* temp = head;
int number = 300; //the place you are looking for
if(temp)
{
    int i;
    for(i = 0 ; i< number && temp->next != nullptr ;i++)
    {
        temp = temp->next;
    }
    if(i == 300)
    {
        //found you value;
        result = temp->value;
    }
}

Upvotes: 1

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