Here is Day 15: Linked List Update problem solution - https://programmingoneonone.com/hackerrank-day-15-linked-list-30-days-of-code-solution.html

C Approach

For Beginners

Node* insert(Node *head,int data) {

struct Node* new_node = (struct Node*) malloc(sizeof(struct Node));
Node *ptr = head ;
new_node->data = data;
new_node->next = NULL;
if(head==NULL){
    return new_node;
}
while(ptr->next!=NULL){
    ptr = ptr->next;
}
ptr->next = new_node;
return head;

}

short and sweet

def insert(self,head,data): 
#Complete this method
self.head = data
print(data,'',end="")

Python 3 Solution; def insert(self,head,data): new_node = Node(data) if head is None: head = new_node else: current = head while current.next: current = current.next current.next = new_node return head

Simple JAVA approach

public static Node insert(Node head,int data) {

    if(head==null){
        head = new Node(data);
    }
    else{
        Node start = head;
        while(start.next != null){
        start = start.next;
    }

    Node newNode = new Node(data);
    start.next = newNode;
    }
    return head;
}