Merge Two Sorted Lists

题目：

Merge two sorted (ascending) linked lists and return it as a new sorted list. The new sorted list should be made by splicing together the nodes of the two lists and sorted in ascending order.

分析：

无

解法：

public class Solution {
    /**
     * @param ListNode l1 is the head of the linked list
     * @param ListNode l2 is the head of the linked list
     * @return: ListNode head of linked list
     */
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        // write your code here
        ListNode dummy = new ListNode(-1);
        ListNode curr = dummy;
        while (l1 != null && l2 != null) {
            if (l1.val < l2.val) {
                curr.next = l1;
                l1 = l1.next;
                curr = curr.next;
                curr.next = null;
            } else {
                curr.next = l2;
                l2 = l2.next;
                curr = curr.next;
                curr.next = null;
            }
        }
        if (l1 != null) {
            curr.next = l1;
        }
        if (l2 != null) {
            curr.next = l2;
        }
        return dummy.next;
    }
}