64. Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list.

The new list should be made by splicing together the nodes of the first two lists.

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        
        ListNode head = new ListNode(0);
        ListNode cur = head;

        while (l1 != null && l2 != null) {
            if (l1.val <= l2.val) {
                cur.next = l1;
                l1 = l1.next;
            } else {
                cur.next = l2;
                l2 = l2.next;
            }
            cur = cur.next;
        }
        if (l1 != null) 
            cur.next = l1;
        } else if (l2 != null) {
            cur.next = l2;
        }
        return head.next;
    }
}