Deleting Node From 2 way linked List

Delete_Node_2WayList(List,Value, Start, End)

Here in this algorithm List is a 2 way linked list containing n nodes. Start and End are the pointers pointing the starting and ending nodes. We have to delete a node from the list which contains Value as its data. Ptr is an intermediate pointer that will be used to traverse the list.

[Checking if List is Empty]

Step 1: if Start=null then

                  return;

[Initializing the Ptr]

Step 2: Ptr = Start

[Searching for the Node which is to be deleted]

Step 3: While Ptr <> null and Ptr->Data <> Value repeat the step

                      i) Ptr = Ptr -> Next

[Checking if search was successful or not]

Step 4: if Ptr = null then

                return;

[Search was successful and Ptr is pointing to the node which is to be deleted]

Step 5:   i) Ptr->Prev->Next = Ptr->Next [Next of Previous node of current node will point the next of  current node] 

              ii) Ptr->Next->Prev = Ptr->Prev [Prev of Next node of current node will point the previous of current node]

[Now Current Node pointing by Ptr is not referenced from list anymore it can be freed now]

             iii) FREE (Ptr)

Step 6: End;