【leetcode】 21. Merge Two Sorted Lists

题目描述：

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.

解题分析：

再基础不过的题了，直接看代码吧^-^

具体代码：

 /**
  * Definition for singly-linked list.
  * public class ListNode {
  *     int val;
  *     ListNode next;
  *     ListNode(int x) { val = x; }
  * }
  */
 public class Solution {
     public static ListNode mergeTwoLists(ListNode head1, ListNode head2) {
         if(head1==null)
             return head2;
         if(head2==null)
             return head1;
         ListNode head=null;
         ListNode current=null;
         if(head1.val<=head2.val){
             head=head1;
             head1=head1.next;
             head.next=null;
         }
         else{
             head=head2;
             head2=head2.next;
             head.next=null;
         }
         current=head;
         while(head1!=null&&head2!=null){
             if(head1.val<=head2.val){
                 current.next=head1;
                 current=current.next;
                 head1=head1.next;
                 current.next=null;
             }
             else{
                 current.next=head2;
                 current=current.next;
                 head2=head2.next;
                 current.next=null;
             }
         }
         if(head1!=null){
             current.next=head1;
         }
         if(head2!=null){
             current.next=head2;
         }
         return head;
     }
 }