Question

Hello, how do I create a new singly linked list by concatenating two existing singly linked list in c++? Thank you!

Answer 1

You have to check these, 3 condition first-:

1.) If list 1 is empty or not.

o> If list 1 is empty then concatenated list will be list 2 only.

2.) If list 2 is empty or not.

o>If list 2 is empty than concatenated list will be list 1 only.

3. If both lists are empty or not.

o>concatenated list will be empty list.

Suppose that our two lists are non-empty linked list, list 1 has start_1 pointer as head pointer and list 2 has start_2 as head pointer.

TO CONCATENATE THE 2 NON-EMPTY LISTS WE NEED TO FOLLOW BELOW STEPS-:

1. Make a pointer 'p' which point to start_1.

2. Take that pointer to last element(node) of list 1 which contains address as NULL.

3. Store the address of first element of list 2 in address field of last node of list 1.

Now you are ready with your concatenated list;)

Algorithm to concatenate 2 linked list-:

node * concatenate (node *start_1, node *start_2)

{

node*p;

                if (start_1==NULL)                            //if the first linked list is empty

                return(start_2);

                if (start_2==NULL)                            //if second linked list is empty

                return (start_1);

                p=start_1;     //place p on the first node of the first linked list

             while (p->next!=NULL)                 //move p to the last node

                                p=p->next;

                p->next=start_2;       //address of the first node of the second linked list stored in the last node of the first linked list return(start_1);

}

C++ CODE

OUTPUT