Dinesh on Java

In this article, we will discuss an algorithm to find the nth node from the end of a singly linked list. First, let’s discuss what is singly liked list.

Singly Linked List

It is a linked list, we can traverse only forward direction. We can’t move to backwards. That means, in a singly linked list, each node in the list has the content and a pointer to the next node in the list. It does not store any pointer to the previous node. To store a single linked list, only the pointer to the first node in that list must be stored. The last node in a single linked list points to nothing.

The nth node from the end of a singly linked list

There are many solutions to this problem are available online specifically in GeeksforGeeks. Let’s discuss one of the solutions to this problem.

Step 1: First, let’s take two pointers to suppose pointer1 and pointer2.

Step 2: Intially initialize these two pointers with the head of the linked list.

pointer1=head;
pointer2=head;

Step 3: Now fix the pointer1 and let’s pointer2 till the nth node from the head of the singly linked list.

while(n > 0){
    pointer2 = pointer2->next;
     n--;
}

Step 4: If pointer2 is the last node of the singly linked then pointer1 is the nth node from the end.

Step 5: If pointer2 is not the last node of the singly liked list then let’s start moving forward pointer1 till pointer2 will reach to the last node of this singly linked list.

while(pointer2->next != null){
    pointer2 = pointer2->next;
    pointer1 = pointer1->next;
}

Step 6: Finally, we found pointer1 as the nth node from the end of the singly linked list.

Code

//Pseudo code


function(head,n){
    pointer1=head
    pointer2=head

    while(n--){
        pointer2=pointer2.next
    }
    //pointer2 reached nth node
    while(pointer2.next is not null){
        pointer2=pointer2.next
        pointer1=pointer1.next
    }

    return pointer1
}

Hope, you have understood this solution for the above find the nth node from the end of a singly linked list. Please share other solutions if you have. :).

Happy learning with us!!!.