MergeTwoSortedLists.java

/**
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.

Hide Tags Linked List
*/

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */

public class MergeTwoSortedLists {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode dummy = new ListNode(0), cur = dummy;
        while (l1 != null || l2 != null) {
            if (l1 == null) {
                cur.next = l2;
                break;
            }
            if (l2 == null) {
                cur.next = l1;
                break;
            }
            if (l1.val < l2.val) {
                cur.next = l1;
                l1 = l1.next;
            } else {
                cur.next = l2;
                l2 = l2.next;
            }
            cur = cur.next;
        }
        return dummy.next;
    }
}