LeetCode_OJ【21】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.

本体思路：比较两个链表当前节点的val值，并将较小值添加到新链上，当其中一个链表比较完了，将另一个链表接到新链的末尾。

java代码如下：

/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
ListNode dummy = new ListNode(-1);
ListNode p = dummy;
while(l1 != null && l2 != null){
if(l1.val < l2.val){
p.next = l1;
l1 = l1.next;
p = p.next;
}
else{
p.next = l2;
l2 = l2.next;
p = p.next;
}
}
if(l1 != null){
p.next = l1;
}
else{
p.next = l2;
}
return dummy.next;
}
}