Merge two sorted linked list

// Merge two sorted linked list - easy - 31/07/2023

// Iterative Approach
class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
         
        ListNode head = new ListNode();
        ListNode ptr = head;
        while(list1!=null && list2!=null){
            if(list1.val <= list2.val){
                head.next = new ListNode(list1.val);
                list1 = list1.next;
            }else {
                head.next = new ListNode(list2.val);
                list2 = list2.next;
            }
            head = head.next;
        }
        while(list1!=null){
            head.next = new ListNode(list1.val);
            list1 = list1.next;
            head = head.next;
        }
        while(list2!=null){
            head.next = new ListNode(list2.val);
            list2 = list2.next;
            head = head.next;
        }
        return ptr.next;
    }
}

// Recursive

class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        if (list1 == null) return list2;
        if (list2 == null) return list1;
        if (list1.val < list2.val) {
            list1.next = mergeTwoLists(list1.next, list2);
            return list1;
        } else {
            list2.next = mergeTwoLists(list1, list2.next);
            return list2;
        }
    }
}