Algorithm to insert node in Simple Linked List

Insert_LinkedList ( List, Node, Start, Value,Data)

In this algorithm List is a linked list having n nodes. Start is a pointer which contains the address of starting node of the list.Node  is the pointer pointing to the new node. Value is the data of a node from list after which the new node is to be inserted.Data is the value which is to be assigned to the data part of new node.

Node->data contains data and Node->Next points next node. In this algorithm following criteria are followed.

• If List is empty Node will be inserted at starting of list
• If Value found in the list than node will be inserted after the value
• else node will be inserted at the end of list

Ptr is an intermediate pointer which points the current node and used to traverse the list

Step 1: i) Node ->data = Data

Step 2: [Check if list is empty then we will insert new node at the starting point.]

            If Start = null then go to step 3 else go to step 4

Step 3: i) Node->Next=null.

            ii) Start=Node

            iii) Return

Step 4: [assigning the 1st node address to Ptr]

                  Ptr = Start

Step 5: While Ptr->Next is Not null repeat

            i) if Ptr->data = Data then go to step i.a else go to step ii)

                     a) Node->Next = Ptr->Next

                     b) Ptr->Next = Node

                     c) Return

           ii) Ptr = Ptr->Next

Step 6: [If Value that was searched not found, in that case inserting Node at the end of List]

            i)Node->Next = null

           ii)Ptr->Next = Node

Step 7: End

Click here for Explanation

According to the Algorithm Consider List is a Linked list and Start is a pointer which is pointing to the starting node of the list. Data is the data which is to be assigned to the data path of the New Node called Node. Value=10 is the data of a node from list after which we have to insert the new node.
Step 1: Node->data = Data

Scene 1: List is Empty

When List is empty

            Since List is empty adding Node to starting of the List
     Start = Node
        Now List will be as shown in below fig.

After inserting node in Empty List

Scene 2: When List contains node having Value=10 in its data field, in the list (As Shown in Image Below.

List 

In this case The node with Value=10 in its data field will be searched as the logic is written in the step 5

Ptr = Start

1st Iteration      Ptr->Next < > null
                   Ptr -> Data = 54
                  since Ptr ->Data < > Value so Ptr = Ptr->Next = 2044

2nd Iteration    Ptr->next < > null

                   Ptr -> Data = 45
                  since Ptr ->Data < > Value so Ptr = Ptr->Next = 5260
3rd Iteration       Ptr->next < > null
                          Ptr->Data = 10
                  since Ptr->Data = Value so
                   [Now we have found our position]

Inserting Node

                       Node->next  = Ptr->next
                       Ptr->next = Node

So Final List is:

Node Inserted

Similarly if node with value doesn't exist or exists at the end of list then new node will be added at the end of list.