## 一、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.

Example

Given `1->3->8->11->15->null`, `2->null` , return `1->2->3->8->11->15->null`.

## 三、解题代码

``````/**
* Definition for ListNode.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int val) {
*         this.val = val;
*         this.next = null;
*     }
* }
*/
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) {
ListNode dummy = new ListNode(0);
ListNode curr = dummy;

while ((l1 != null) && (l2 != null)) {
if (l1.val > l2.val) {
curr.next = l2;
l2 = l2.next;
} else {
curr.next = l1;
l1 = l1.next;
}
curr = curr.next;
}

// link to non-null list
curr.next = (l1 != null) ? l1 : l2;

return dummy.next;
}
}
``````