def mergeLists(head1, head2): dummy = SinglyLinkedListNode(0) tail = dummy

while head1 and head2:
    if head1.data < head2.data:
        tail.next = head1
        head1 = head1.next
    else:
        tail.next = head2
        head2 = head2.next
    tail = tail.next

tail.next = head1 if head1 else head2
return dummy.next

Problem explanation is incorrect in the example. There is no 7 in either input LinkedList.

Merging two sorted linked lists is a classic linked list problem, often asked in technical interviews and widely used in algorithms like merge sort. Cricbet99 Green Sign Up

    static SinglyLinkedListNode mergeLists(SinglyLinkedListNode head1, SinglyLinkedListNode head2) {

         SinglyLinkedListNode newList = null;

    if(head1.data < head2.data){
        newList = new SinglyLinkedListNode(head1.data);
        head1 = head1.next;
    }else{
        newList = new SinglyLinkedListNode(head2.data);
        head2 = head2.next;
    }

    var head = newList;

    while(head1 != null && head2 != null){

        if(head1.data < head2.data){
            newList.next = new SinglyLinkedListNode(head1.data);
            head1 = head1.next;
        }else{
            newList.next = new SinglyLinkedListNode(head2.data);
            head2 = head2.next;
        }
        newList = newList.next;
    }
    newList.next = (head1 != null) ? head1 : head2;


    return head;
}

Hi all, here my recursive solution in Java 8.

    static SinglyLinkedListNode mergeLists(SinglyLinkedListNode head1, SinglyLinkedListNode head2) {
        if(head1== null && head2== null)
            return null;
        if(head1 == null)
            return head2;
        if(head2 == null) {
            return head1;
        }
        SinglyLinkedListNode result = null;
        if(head1.data< head2.data){
            result = head1;
            result.next = mergeLists(head1.next, head2);
        } else {
            result = head2;
            result.next = mergeLists(head1, head2.next);
        } 
        
        return result;
    }