LeetCode-Hot100 27.合并两个有序链表

一道非常经典的链表算法题，核心在于头节点的处理和一个链表遍历完毕后另外一个链表的处理

注意if和后面的else，如果写两个if的话就会错误

示例代码如下

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode dummy = new ListNode();
        ListNode cur = dummy;
        while(list1!=null&&list2!=null){
            if(list1.val<list2.val){
                cur.next = list1;
                list1 = list1.next;
            }else{
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;
        }

        cur.next = list1!=null?list1:list2;
        return dummy.next;
    }
}